APIs Are a Mess. So We Open-Sourced a Reference for 3,122 of Them.
We open-sourced the API reference we built to make integrations less painful: 3,122 apps and 75,075 endpoints in one searchable format.
At MindCloud, we have spent the last five years living with a problem that every integration team eventually runs into: APIs are supposed to make software work together, but the experience of integrating them is often far more difficult than it needs to be.
The trouble is rarely the idea of an API. It is everything around it.
One application uses bearer tokens; another uses OAuth; another expects a custom header. One paginates with cursors, another with offsets, another with page numbers. Dates arrive in different formats. Filters and sort rules change from vendor to vendor. Response shapes, error handling, rate limits, and even names for the same business object all vary.
That inconsistency creates friction for developers and a worse experience for the people who depend on their software to work together. And it has not gone away just because the companies behind the APIs have gotten bigger. Some of the most important systems in business still have some of the hardest APIs to integrate with.
We built MindCloud because we wanted to make that work better. Along the way, we created a consistent internal API surface that gives every supported application the same treatment: how it authenticates, how it paginates, what it accepts, what it returns, and how it maps back to the vendor’s native API.
Today, we are open-sourcing that work.
The Universal API Reference
The Universal API Reference is a searchable, machine-readable reference for 3,122 apps and 75,075 endpoints.
Every endpoint has its own file. Every app is documented through the same set of conventions. That includes authentication, request and response formats, pagination, filtering, sorting, HTTP behavior, and a mapping back to the vendor’s own endpoint and documentation.
It is deliberately simple to use. You can clone the repository and search it with the tools developers already have:
# Find every app with a refund-related endpoint
rg -l "refund" apis# See how a specific API handles pagination
rg "pagination" apis/s/stripe/universal-api/README.md -A 3That is useful because so much integration research is still a scavenger hunt. A developer may know they need to issue a refund, update a contact, create an invoice, or pull paginated records, but still have to open multiple vendor documentation sites just to learn what each system calls the operation and how it behaves.
The reference is meant to make that work less mysterious.
Why we are sharing it
This is not a scraped directory of public documentation. It is a nightly mirror of the machine-readable specification behind MindCloud’s integration gateway—the same specification we use to build and operate integrations in production.
Our systems run at an annualized rate of approximately 1.85 billion API calls. That scale matters because it gives us a very practical definition of good documentation: it needs to match what the API actually does.
When a vendor changes an endpoint, when pagination behaves differently than expected, or when an argument is documented incorrectly, real workflows can break. We investigate those issues and update the specification that powers them. Those improvements then flow into this public reference.
We built this because we needed it ourselves. We are sharing it because we think the underlying map should be useful to more than one company.
Use it however it helps
You do not need a MindCloud account to use the repository.
If you are integrating directly with a vendor, it can be a faster way to orient yourself in that vendor’s API. If you are deciding which platforms support a particular capability, you can search across the collection rather than repeat the same research thousands of times. If you are building developer tools or AI agents, the catalog, endpoint files, and llms.txt index provide structured context that is much more useful than sending an agent into a tangle of inconsistent documentation sites.
The documentation is available under the CC BY 4.0 license. Use it, search it, build on it, and tell us what would make it more useful.
The map is open. The execution layer is optional.
We also want to be direct about the connection to MindCloud.
The open-source reference is the map of this API surface. For teams that want to execute against supported applications through a single interface, MindCloud offers a hosted Universal API and MCP built on the same underlying work.
But the repository is meant to stand on its own. It is a resource for developers, integration teams, and builders who are tired of rediscovering the same API differences over and over again.
Help us make it better
APIs change constantly, and this reference will keep changing with them. If you find an error, see an app we are missing, or have a question you think should be easy to answer across APIs, open an issue.
And if this is useful to you, please star the repository and share what you build with it.
