7 Best Online Coaching Platforms and Tools for 2022

Updated Aug 8, 2022.

Are you a coach looking for the best online coaching platforms and coaching tools? Check out this article to find out the seven best options for 2022!

Thinkific icon

Thinkific

A great online coaching platform offering all the features you need to run a successful online coaching business. Thinkific is easy to use, has incredible features, and is affordable.
Kajabi icon

Kajabi

Best-in-class online coaching software that enables coaches to build courses, create membership sites, and sell digital products. Kajabi has an intuitive interface and comes with great marketing features.
Acuity Scheduling icon

Acuity Scheduling

Robust online coaching software for managing appointments and keeping your clients on track. Plus, its powerful features make it easy to streamline your business operations.
TrueCoach icon

TrueCoach

The perfect online coaching software for effective coaching businesses. With TrueCoach, you can create tailored training programs for your clients and manage your business quickly and efficiently.
Noomii icon

Noomii

The world's largest and most effective coaching marketplace, connecting talented coaches with clients worldwide. If you're a professional coach, there's no better place to find clients than Noomiii.

Our work is supported by affiliate commissions.

It's no secret that online coaching is on the rise. In fact, the global online coaching market is expected to reach $350 billion by 2025.

With so many people looking for guidance and support online, it's no wonder that many online coaching platforms and tools are available to help coaches move their coaching business online.

So, if you're thinking of building a successful coaching business or just looking for some online coaching tools, check out my list of the seven best coaching platforms and tools for 2022!

Types of Online Coaching Platforms and Tools to Grow Your Practice

Life coaches, health coaches, and similar professionals often ask about the best online coaching platforms and tools to grow their practices.

Answering this question is not simple because many different online coaching platforms are available, each with its features and benefits.

There are many different types of online coaching tools available to help you build your coaching practice. 

To build a successful online coaching practice, online coaches often need the following functionality:

These are just a few different types of coaching websites and online coaching tools available to help you grow your coaching practice. 

Consider your needs and budget when choosing the right platform or tool for your coaching business. Also, read reviews from other coaches to get an idea of which platforms and tools are the best fit for you and your coaching business.

Best Online Coaching Platforms and Tools

Today, coaching clients online is easier than ever before. Several great online coaching platforms and tools make it easy to connect with clients, track progress, and deliver results to unlimited clients.

Here are a few great options if you're looking for the best online coaching platforms.

1. Thinkific

Best Online Coaching Platform for Solopreneurs

Editor's Take
9.2 out of 10
Best For
Solopreneurs
Price
$39 – $499
Annual Discount
20%
Promotion
Free Plan

Thinkific is a compelling yet easy-to-use online course platform that makes creating and delivering high-quality online coaching programs a breeze.rnThe wide range of features and customization are the top reasons I recommend this platform for professionals at large organizations and business coaches who don't have much experience creating video training.rnEven more appealing is the fact that there are no transaction fees on any pricing plans.rnWhether you're a corporate training coordinator or a solopreneur, Thinkific would be my top recommendation for an online coaching platform.rn

Try Thinkific

Thinkific is the simplest and most effective online coaching tool to help sell your online coaching services. 

You can easily create and sell courses, deliver engaging live lessons, and build a thriving community of students.

With their world-class support, you can be confident that you're delivering the best online learning experience possible.

Overall, Thinkific is one of the best coaching platforms for experts who want to share their knowledge, businesses who need to train their staff, and anyone who wants to make a difference with their expertise.

Key Features

  • Secure hosting and enterprise-ready platform: Thinkific provides secure and reliable cloud hosting with 24/7 monitoring and an SSL certificate. And because it is built on a responsive design platform, your courses will look great on any device. The peace of mind with these features lets you focus on building your training programs and workouts rather than spending your valuable time behind the curtains.
  • Industry-leading support: The platform offers industry-leading support to its customers via a helpful team of qualified professionals and an award-winning customer service team. Such a high level of support guiding you along the way is ideal, especially for non-technical coaches and trainers.
  • Unique domains and advanced customizations: You can add professional domains easily and completely replace the Thinkific branding with personal branding. This makes it perfect for those who want to create a professional-looking site without investing additional resources for hosting or design services.
  • Progress tracking: Thinkific provides detailed reporting, which actively helps track performance and client results to ensure they are on track to complete the course. The platform also offers comprehensive quizzes, surveys, and exams for all types of classes. All these elements provide an engaging and valuable learning experience for your students.

Pricing

Thinkific-Pricing-Plan-1

Thinkific has four pricing models: Free, Basic, Pro, and Premier. These plans range from $49 to $499 per month. 

You also have the option for a Growth add-on on the Pro plan if you need to access the high-powered features for an additional $50 per month on top of the Pro Plan. 

The Basic plan is best for Solopreneurs and beginners. The Pro plan paired with the Growth add-on is best for SMEs (subject matter experts). And the Premier plan is perfect for larger organizations.

Pros

  • Robust platform with a helpful and highly-intuitive interface.
  • Very responsive website on all screen and platform sizes.
  • Thinkific Academy has premium webinars with tips and tricks from course experts to help you elevate your courses and content.
  • A community of 50,000+ pros that are always ready to help with any question you have.

Cons

  • The lack of an integrated email and social media marketing functionality is the only drawback of Thinkific. This can be easily overcome by offering integration with an external service such as Mailchimp, Zappier, Buffer, Hootsuite, etc. The idea behind this is simple: I want to do as much as possible while remaining inside the platform to market my courses efficiently.
Try Thinkific

2. Kajabi

All-In-One Coaching Platform

Editor's Take
8.9 out of 10
Best For
Executive Coaching
Price
$149 – $399
Annual Discount
20%
Promotion
Free Trial

Kajabi is an all-in-one online coaching software that gives you everything you need to build, launch, and market your courses online. rnWith Kajabi, you can create beautiful course sites, landing pages, and email marketing campaigns optimized for conversion.rnOverall, I think Kajabi is the perfect platform for experts and authors who want to share their knowledge, businesses who need to train their staff, and anyone who wants to make a difference with their expertise.rn

Try Kajabi

Kajabi is a powerful tool that allows you to quickly and easily create professional-looking courses. 

The interface is simple and user-friendly while providing all of the features you need to create high-quality courses.

The platform offers a beautiful customer experience with a responsive team of professionals always ready to help. 

You also get access to an extensive knowledge base and a community of experts who can answer any of your questions.

With the inclusion of a course builder, website builder, e-commerce and shopping cart, e-mail service provider, and landing pages and funnels, Kajabi strives to provide everything you need to successfully build and launch your courses.

Key Features

  • Course builder:  With Kajabi's course builder, you can easily create and sell online courses. The intuitive drag-and-drop interface makes adding content and building your course simple, and you can even use videos and quizzes to engage your students.
  • Website builder: Using the website builder, you can create a beautiful website for your coaching business with no programming required. Just choose from one of their many templates and add your text, images, and videos. You can also sell products and courses directly from your website using Kajabi.
  • E-commerce and shopping cart: Equipped with an extensive range of powerful e-commerce features, Kajabi lets you sell coaching packages from your website. You can add products to your shopping cart, and customers can pay using PayPal or a credit card. Plus, Kajabi integrates with popular shipping providers so you can quickly ship products to your customers.
  • E-mail marketing: Kajabi lets you send your customers newsletters, special offers, and other updates through its powerful email marketing functionality. This is an excellent way to build and maintain long-lasting customer relationships and grow your business.
  • Built-in Payment Processing: The online coaching platform includes built-in payment processing so you can efficiently process payments for your products and courses. Kajabi integrates with PayPal and Stripe, so you can easily accept payments from your customers.

Pricing

Kajabi - Pricing Plan

Kajabi has three pricing models: Basic, Growth, and Pro. 

These plans range from $149 to $399 per month. All plans come with a 14-day free trial.

Pros

  • Kajabi is easy to set up and even easier for your students to navigate. You can create courses in minutes, and they will be easy to follow with an intuitive user interface.
  • The coaching platform has many integrations, so you can easily connect with other tools you're likely using for your business.
  • It has great templates and a wide range of customization options to make your courses look professional and branded.
  • The robust membership capabilities allow you to create and manage memberships for your courses quickly.
  • SEO optimization is built-in, so you can be sure that your courses will be easy to find online.

Cons

  • While Kajabi is an excellent platform with many features, I find its email functionality clunky and hard to use. Creating emails that look professional and optimized for conversion can be challenging. The email service provider lacks some features standard in other providers, such as automated email sequences. This can make it challenging to nurture leads and convert them into paying customers.
  • The Kajabi online coaching platform can be pricey for some businesses, especially those just starting.
  • Although the templates and customization options are great, they may not be enough for some businesses who want a custom look for their courses.

3. Acuity Scheduling

Best Coaching Platform for Scheduling Appointments

Editor's Take
8.2 out of 10
Best For
Online Scheduling
Price
$14 – $45
Annual Discount
6% – 10%
Promotion
Free Trial

I like that Acuity Scheduling is explicitly designed with coaches in mind, as it offers many features geared towards this group. rnI also like that this online coaching platform integrates with several different calendar applications, making it easy to keep track of appointments and coaching sessions.rnOverall, Acuity Scheduling is a helpful tool for coaches looking to manage their time and clients better.rn

Try Acuity Scheduling

Acuity Scheduling is a cloud-based appointment scheduling software that allows coaches to manage their time and coaching practice effectively by enabling them to schedule appointments online.

This coaching platform offers many features, including online booking, automated appointment reminders, calendar sync, and more.

Because of its extensive feature set, Acuity Scheduling is an ideal solution for coaches who want to streamline their scheduling process.

Key Features

  • Email and SMS reminders: With Acuity Scheduling, you can set up email or SMS reminders for your clients, so they know when their appointment is coming up. This can help to make sure that they don't forget about their appointment, and it also helps to keep them on track.
  • Auto time zone adjustment: This feature is handy if you have clients in different time zones. Acuity Scheduling will automatically adjust the time of your appointments so that they are in the correct time zone for your client. This can save you time and hassle when scheduling coaching sessions.
  • Intake-forms: Acuity Scheduling allows you to create intake forms for your clients. This is a great way to collect information from your clients before their appointment. Intake forms can help you to understand your clients and their needs better, and they can also help to save time during the actual meeting.
  • Embeddable directly to your website: Acuity Scheduling can be embedded directly into your website. This is a great way to make it easy for your clients to book appointments with you. It also helps keep your brand front and center, making your clients more likely to use your scheduling system.
  • Cloud sync: Acuity Scheduling integrates with many different calendar applications. This makes it easy to keep track of your appointments and allows you to share your schedule with others easily. Calendar sync can be a great way to stay organized and ensure everyone is on the same page.

Pricing

Acuity Scheduling - Pricing Plan

Acuity Scheduling offers three pricing models: Emerging, Growing, and Powerhouse. 

These plans range from $14 to $45 per month. All plans come with a 7-day free trial.

Pros

  • Acuity Scheduling is efficient and easy to use – making it an excellent choice for businesses of all sizes. With its simple and intuitive interface, Acuity Scheduling can be quickly learned and operated by anyone.
  • The coaching platform allows businesses to track customer data – providing valuable insights into customer behavior. This information can improve marketing efforts and target potential new customers.
  • Provides businesses with multiple calendars – giving them the flexibility to manage their schedules as needed.
  • Integrates with many popular business applications – making it even easier to use. This includes applications such as QuickBooks, Google Calendar, and Outlook.

Cons

  • It can be challenging to find specific functions, such as the ability to export your calendar to other platforms. 
  • Some users also find it difficult to block off appointments. For example, if you need to cancel an appointment, it can be challenging to do so without disrupting the rest of your schedule.
Try Acuity Scheduling

4. TrueCoach

Best Coaching Platform for Fitness Instructors

Editor's Take
8.0 out of 10
Best For
Fitness Instructors
Price
$0 – $89
Annual Discount
up to 24%

TrueCiach is easily the best coaching platform for fitness instructors. rnIt's simple to use and intuitive, which is excellent for busy people who don't have much time to waste.rnThere are some things I don't like about it, but overall it's a great tool. rnFor example, I wish it had a way to make changes to your coaching program on the mobile app too, but other than that, it's been great.rnI would recommend TrueCoach to anyone looking for an easy way to manage their fitness coaching business. rnIt's ideal for personal trainers and health and wellness coaches who want to quickly and easily communicate with their clients, track clients’ progress, offer customized training programs, and manage payments.rn

Try TrueCoach

TrueCoach is a modern coaching platform that makes it easy for coaches and athletes to connect and work together.

It provides a simple and effective way for coaches to create training programs, track clients’ progress, and communicate with their athletes. 

This online coaching management platform also offers a coaching app, so athletes can log their workouts, see their progress, and message their coach on the go.

Whether you're a coach who wants to manage your athletes' training more effectively or an athlete who wants to stay on top of your progress and communicate with your coach, TrueCoach is the perfect solution.

Key Features

  • Workout builder: The TrueCoach workout builder is an excellent way to create custom workouts and individualized training programs for your clients. Not only does it allow you to choose the exercises, but you can also set the number of reps, sets, and weight for each. This ensures that each client gets a workout specifically tailored to their needs.
  • Video exercise library: The video exercise library is an excellent resource for coaches. It includes over 300 exercises, each with a video demonstration. Thus, it is easy to find the perfect exercise for your client and ensure that they are doing it correctly.
  • Client management: TrueCoach's client management system is second-to-none. With the help of this feature, you can easily keep track of all of your clients, keep client contact information intact, and track client progress. This level of client tracking and management makes it easy to stay organized and ensure that you provide the best possible service to your clients.
  • Coaching program builder: This is a great tool for professional coaches who want to create comprehensive coaching programs for their clients. It allows you to add exercises, nutrition plans, and other resources. Thanks to this feature, you can easily create complete coaching programs to help your clients reach their goals.
  • Nutrition tracking: The nutrition tracking feature in TrueCoach is an excellent way to ensure that your clients get the nutrients they need. Track your clients' food intake and ensure they meet their nutritional needs. This is a valuable tool for coaches who want to help their clients improve their overall health.

Pricing

TrueCoach - Pricing Plan

TrueCoach has four pricing plans: Xplorer, Starter, Standard, and Pro. 

These plans range from $0 to $89 per month. All plans come with a 14-day free trial.

On top of that, TrueCoach’s basic plan, Xplorer, is free to use as long as you’re using it for one active client.

You would need to upgrade to one of their paid plans to take on more clients.

Pros

  • TrueCoach provides increased accountability for coaches – creates a system where coaches can track their progress and performance and receive feedback from their clients.
  • Increased motivation is another benefit of using TrueCoach. The platform provides coaches access to a wealth of resources and materials to help them stay motivated and inspired while working with their clients.
  • Enables you to personalize your coaching process – tailor your approach and methods to each client based on their specific needs and goals.

Cons

  • It can be frustrating to get help when you need it. I have found that the customer service team is often unresponsive or slow to help. This can be frustrating when you are trying to figure out a problem or need help with something.
  • Navigation is cumbersome, especially for new coaches. There are a lot of features and options, and it can be hard to figure out how to use them all.
Try TrueCoach

5. Noomii

Ideal Coaching Marketplace for Getting Leads

Editor's Take
7.8 out of 10
Best For
Professional Coaches
Price
$447/yr
Annual Discount
N/A

If you're in the coaching profession, Noomii is worth checking out. It's the best platform for professional coaches who want to build a coaching practice.rnNoomii is especially well-suited for group coaching. The platform makes it easy to connect with multiple coaches and create groups. This is a great way to build a coaching community and get feedback from other coaches.rnI highly recommend Noomii to any coach who wants to build a professional coaching practice.rn

Try Noomii

Noomii is one of the best online coaching companies that help people create and sustain a successful coaching business. 

Noomii also offers group coaching, allowing coaches to connect with and learn from each other’s coaching practice.

The company also offers free resources, such as articles and ebooks, to help people learn more about offering group coaching programs.

Key Features

  • Networking: Networking is vital for any business, but it is especially crucial for coaches. Noomii has a comprehensive database of qualified support coaches that can help you expand your reach and grow your coaching business.
  • Blog and podcast series: You also have access to a blog and podcast series that can help you learn more about running an effective coaching business and provide you with valuable insight and tips. The blog and podcast series are informative and entertaining and can help you better understand the coaching industry. This is a great way to stay up-to-date on the latest industry news and trends.
  • Coaching management: Noomii supports coaches at every stage of their business, from the initial set-up to ongoing coaching management. Their blog and podcast series offer valuable tips and advice, and the coaching program helps coaches sustainably build their own coaching business.
  • Client testimonials: This is where Noomii shines, especially for coaches just starting. Client testimonials are a great way to market yourself and attract new clients. Noomii makes it easy for you to get testimonials from your past clients, which can be a valuable asset in your coaching business.
  • Visibility: With Noomii, you can be confident that your coaching business will be visible to those who matter most – your potential clients! Their regional search feature makes it easy for clients to find coaches in their area, and the comprehensive database ensures that you’ll be included in search results.
  • Credibility: Get access to the right coaching tools you need to build credibility and trust with potential clients. The money-back satisfaction guarantee shows that Noomii stands behind its services, and the client testimonials provide social proof that coaching with Noomii can lead to success.

Pricing

You can get listed for free on Noomii, but to make the most of this online coaching marketplace, you'll want to purchase their yearly membership, which costs $447/yr.

Plus, their membership comes with a 100% money-back guarantee, in that if the clients you find through their site don't make up for the cost of your membership within a year, they will refund you the entire amount.

Pros

  • It provides an opportunity to get listed in an extensive database of qualified professional coaches from various industries.
  • Coaches can communicate directly with clients through the messaging system.
  • Allows you to connect with other coaches in your industry and build your network.
  • As a “Featured Coach” on Noomii, you'll have increased exposure to potential clients, which can help you empower your coaching business.
  • The platform provides access to training courses so you can continuously improve your skills.

Cons

  • The platform's back end is not as extensive as other coaching management platforms – you may need to use third-party tools, like marketing tools, in conjunction with Noomii for additional features like creating courses and email marketing.
  • Pretty competitive – the marketplace structure can be challenging to stand out in if you do not have a robust lead generation strategy.
Try Noomii

6. Mighty Networks

Mighty Networks - Create communities, sell memberships, and grow your course sales

Ideal Coaching Management Platform

Mighty Networks is a popular online coaching management platform that enables coaches to manage their coaching programs and provides them with the tools they need to deliver a great coaching experience to their clients.

The platform offers a variety of features, including a client management system, a coaching program builder, and a payment gateway.

Mighty Networks also allows coaches to connect with their clients and build a community around their coaching business.

Key Features

  • Powerful coaching tools: This platform provides everything you need to coach your clients online effectively. With features like live streaming, video chat, messaging, and event management, you can connect with clients in real-time and deliver great coaching programs.
  • Client engagement and management: Mighty Networks has excellent client management and engagement tools. You can have a private or public network and use live streaming and video features to connect with clients. There are also chat and messaging tools and Zoom integration for events.
  • Multiple monetization options: With this platform, you can access various options for monetizing your coaching business. You can charge people to join your group, access your community, or subscribe to your courses. This gives you much control over how you make money and who gets to participate in your coaching programs.
  • Community: Mighty Networks is a great place to be a coach. You can find everything you need all in one place. Not only do you get a perfect course builder, but you also get a community space that is just for coaches. This is perfect for getting help and advice from other coaches and finding new coaching programs and courses.

Pricing

Mighty Networks - Pricing Plan

Mighty Networks offers three pricing plans: The Community Plan, The Business Plan, and The Mighty Pro.

The Community Plan is $33/month, the Business Plan is $99/month, and the Mighty Pro plan is quoted individually. All plans come with a free trial.

Monthly prices are lower than yearly, so I suggest starting with a monthly plan. You can always switch to a yearly plan later on.

The Community Plan is best for individuals or small businesses just starting with Mighty Networks.

Businesses ready to scale their Mighty Network and need more features and support should go with The Business Plan.

The Mighty Pro plan is custom-tailored to the needs of larger businesses and organizations.

Pros

  • It offers multi-channel content delivery, making it a versatile coaching platform for coaches.
  • Most coaches appreciate the support and regard Mighty Networks as a highly-supportive platform with a community-first approach.
  • It provides coaches with many growth opportunities to expand their coaching practice as their business grows.
  • Mobile app access makes the platform convenient for coaches who want to be able to deliver content on the go.

Cons

  • It lacks features for awarding certificates and conducting quizzes that many other online coaching tools offer. This isn't conducive for coaches who want to gamify the learning experience for their students.
  • I also find this coaching platform complicated for beginners. The interface isn't the most intuitive, and finding your way around the site can be tricky.
Try Mighty Networks

7. Satori

Best Administrative Solution for Coaches

Satori - Design and Deliver Your Signature Coaching Program

Satori is an online coaching software that helps with coaching management and payments. It enables coaches globally to run effective coaching businesses by providing a simple and easy-to-use interface.

Using Satori, coaching businesses can securely manage client details, set recurring payments, and track goals and progress.

Compared to other coaching tools, Satori is more affordable and offers a free trial.

Key Features

  • Appointment scheduling: Satori's appointment scheduling feature is designed to help coaches manage their time and appointments more effectively. By allowing coaches to see their schedule in one place and quickly add, edit, or cancel appointments, Satori makes it easy for coaches to keep track of their coaching business.
  • Billing & invoicing: When running a coaching business, coaches have to deal with a lot of paperwork and hassle when it comes to billing and invoicing their clients. With Satori, coaches can easily create and send invoices to their clients with just a few clicks. This way, coaches can focus on what they're good at – coaching!
  • Program management: If you're running a coaching program, whether a group program or an individualized program, Satori can help you manage it effectively. Using Satori, you can easily keep track of your programs, schedule appointments, and send invoices all in one place. This is ideal for coaches who have a tight schedule and need to manage their programs efficiently.
  • Versatile coaching options: Satori offers a variety of coaching options for coaches to choose from. Whether you're looking for group coaching, individualized coaching, or even virtual coaching, Satori has you covered. Plus, whether you offer life coaching, health and wellness coaching, or business coaching, Satori can help you craft effective coaching packages for your clients.

Pricing

Satori - Pricing Plan

Like the other coaching platforms on this list, Satori offers monthly and annual subscriptions. There are four plans: Starter, Builder, Trailblazer, and Pro.

These plans range from $12 to $67 per month or $10 to $56 per month when paid annually.

If you go for the annual plans, you will be getting two months free.

Pros

  • Streamlines the process of follow-up and communication between coaches and clients, which can save time and energy.
  • Automates the administrative side of group coaching. This includes helping schedule workshops and classes and delivering stellar client experiences.

Cons

  • It does not offer any features for creating online coaching courses or resource libraries.
  • It lacks features for online small groups or communities, so you will need to create these on your own or use a third-party platform.
Try Satori

FAQs

What are online coaching platforms?

Online coaching platforms are software that offers technical and administrative support to individuals and organizations who wish to provide online coaching services. Coaches can use these platforms to connect with clients, set up coaching sessions, and deliver coaching content.

Why do coaching companies need a coaching platform?

A coaching platform helps coaching companies manage their business and connect with clients. It provides a central place for managing coaching programs, scheduling appointments, tracking payments, and providing coaching resources to clients.

This level of streamlining and automation can save coaching companies time and money, which can be reinvested into growing their business.

What Is The Best Online Coaching Platform?

Coaching platforms have become increasingly popular as more people look for ways to improve their lives.

When it comes to choosing one, it can be tricky, given the wealth of these tools in the market.

So, which is the best online coaching platform?

The answer to this question depends on your individual needs and preferences. But for your convenience, here's my list of 5 best online coaching platforms:

Best Overall

Thinkific

A great online coaching platform offering all the features you need to run a successful online coaching business. Thinkific is easy to use, has incredible features, and is affordable.
All-In-One Platform

Kajabi

Best-in-class online coaching software that enables coaches to build courses, create membership sites, and sell digital products. Kajabi has an intuitive interface and comes with great marketing features.
Best for Scheduling Appointments

Acuity Scheduling

Robust online coaching software for managing appointments and keeping your clients on track. Plus, its powerful features make it easy to streamline your business operations.
Best for Customized Training

TrueCoach

The perfect online coaching software for effective coaching businesses. With TrueCoach, you can create tailored training programs for your clients and manage your business quickly and efficiently.
Best for Getting Clients

Noomii

The world's largest and most effective coaching marketplace, connecting talented coaches with clients worldwide. If you're a professional coach, there's no better place to find clients than Noomiii.

If you would like to know more about these online coaching tools, check out the following guides:

Martin Luenendonk

Editor at FounderJar

Martin loves entrepreneurship and has helped dozens of entrepreneurs by validating the business idea, finding scalable customer acquisition channels, and building a data-driven organization. During his time working in investment banking, tech startups, and industry-leading companies he gained extensive knowledge in using different software tools to optimize business processes.

This insights and his love for researching SaaS products enables him to provide in-depth, fact-based software reviews to enable software buyers make better decisions.