-
n8n
Free and source-available fair-code licensed workflow automation tool. Easily automate tasks across different services.
-
lago
Open Source Metering and Usage Based Billing API ⭐️ Consumption tracking, Subscription management, Pricing iterations, Payment orchestration & Revenue analytics
-
SurveyJS
Open-Source JSON Form Builder to Create Dynamic Forms Right in Your App. With SurveyJS form UI libraries, you can build and style forms in a fully-integrated drag & drop form builder, render them in your JS app, and store form submission data in any backend, inc. PHP, ASP.NET Core, and Node.js.
Creating automations: n8n (similar to Zapier but self-hostable for free) - here you can find a n8n workflow to rate limit your APIs
Lago might be worth trying out as well - https://www.getlago.com/