All the flexibility of an API, without writing any of the code. A powerful build-anything-you-want HTML API for payments, user authentication and customer management. It's like using Stripe, but without having to write any code.

See real examples.

Try Demos

You write and control all the HTML and CSS code.

This isn’t an embeddable form. This is your own code on your own site.

Yes, really.

Flexkit handles all payment and validation logic.

Just drop in our script tag and Flexkit will find and process all your payment forms for you. No need to write any Javascript.

Process one-off payments and/or subscriptions.

Easily build your own shopping cart. Charge for one-off payments and subscription payments in the same order!

Built-in user authentication and sign-up system.

No need to write any code to handle user sign-ups or log-ins. Just make a HTML form and Flexkit will handle everything else!

Build it yourself

You handle the UI, Flexkit handles everything else.

With Flexkit you can quickly turn any of your plain HTML forms into working payment, sign up and sign in forms. Simply build your forms how ever you'd like, then add a few Flexkit HTML attributes and the Flexkit code snippet to your page. All your forms will magically work! Whether you're accepting payments or signing up new customers/subscribers, it all just works. No API integrations or coding necessary!

Flexible Payments

Build and charge for anything with ease.

Want to add a simple payment form to your site? Or maybe you want a complex checkout form with multiple products and subscriptions? Flexkit makes it easy. Just build the HTML form and Flexkit takes care of the rest!


Hassle-free recurring billing.

Easily add any number of payment plans at any billing interval for your customers to pick from when they sign up. You can create free or paid plans, set free trials, custom billing dates, and more. All the payments, email receipts, and sign up forms are handled by Plasso. You don't have to code anything.

User Authentication

Flexkit handles all the complexity.

Flexkit automatically turns your plain HTML sign up/sign in forms into a real user authentication system. All the logic to determine if a customer has entered their correct login information is handled by Flexkit. When a signup or login attempt is successful we pass their information to you and they are automatically granted access to your protected content. You don't need to code anything to make this happen, our Flexkit server-side client handles it all for you.

Easy Integration

After building your own payment forms on your site, simply copy and paste the following line of code and you’re done! No other configuration neccessary!

... your content ...<script src="https://plasso.com/embed/flexkit.1.1.js"></script></body>

Flexkit client

If you’re using Flexkit to handle authentication (user signups and logins) you’ll need to grab our Flexkit back-end client. It will automatically facilitate secure authentication, authorization and manage access to your content for you. All you need to do is drop it into your server-side codebase.

You do not need to use this client if you’re only using Flexkit to handle payments and/or subscriptions.

Get the client:   Javascript    PHP    Ruby    Go

Learn more about Flexkit integration

Read the Docs Help Center

Complex payments made easy

Payments require lots of development and API integrations. You don't have time for that. You just want to control the UI. Flexkit makes that a reality.

Drop-in and you're done

Simply copy/paste a code snippet and your sign up, sign in and payment forms will be completely ready for customers.

Perfect for SaaS

Focus on building features that bring value to your customers, not writing and managing a billing/payment system.

Collect custom data

Add any number of form fields to your sign up and payment forms to gather more data from your customers.

Customer dashboard

With the Plasso dashboard you'll be able to see and manage all the details of your customers and members.

Automatic emails

Receipts, shipment notifications, upcoming charges, and more are all automatically sent to your customers.

Analytics and reports

Keep track of sales and new sign-ups at a glance.

Export data

All your sales and customer data can be exported with one click.

256-bit SSL security

All transactions and payment forms are secure and encrypted.