# API Change Feed

> Breaking changes, deprecations and security fixes for 38 popular APIs and SDKs (LLM SDKs, Stripe, Next.js, React, Node, Python frameworks, cloud SDKs). Built for AI coding agents whose training data is out of date. Paid per call with x402 (USDC on Base); no account or API key.

## How to use
Call GET /v1/upgrade-check?package=<npm or pypi name>&from=<version your code targets> before writing code against a library you may know only from older training data. It returns every breaking change, deprecation and security fix between that version and the latest release, plus every major version crossed. Use GET /v1/sources (free) to see which packages are tracked, and GET /v1/preview (free) to check freshness. Paid routes answer HTTP 402 with x402 payment terms; any x402 client pays in USDC and retries automatically. Invalid input, unknown packages and sources without version data return 4xx and are never charged. Each record includes "evidence": the sentence that triggered its label. A same-API sandbox at /sandbox/v1 takes free test USDC (Base Sepolia) and serves data delayed 30 days, for integration testing. An MCP server with the same tools is at /mcp.

## Free
- [Sources](https://changefeed.anthonyzilar.workers.dev/v1/sources): every API/SDK we track, with package names you can query by.
- [Preview](https://changefeed.anthonyzilar.workers.dev/v1/preview): latest five breaking/deprecation/security headlines.
- [OpenAPI](https://changefeed.anthonyzilar.workers.dev/openapi.json) with x-payment-info on paid operations.
- [MCP server](https://changefeed.anthonyzilar.workers.dev/mcp) (Streamable HTTP): free tools list_sources and preview_changes; paid tools upgrade_check, get_changes and digest (x402).

## Paid
- [Upgrade check](https://changefeed.anthonyzilar.workers.dev/v1/upgrade-check?package=next&from=14.2.0) ($0.01): what broke, what's deprecated and what's patched since your version.
- [Changes](https://changefeed.anthonyzilar.workers.dev/v1/changes?source=stripe&kinds=breaking,deprecation) ($0.005): filterable change records by source, date and kind.
- [Digest](https://changefeed.anthonyzilar.workers.dev/v1/digest?since=2026-10-01) ($0.02): everything breaking across all tracked sources since a date.

## Record shape
{ source_id, version, published_at, kinds: [breaking|deprecation|security|release], title, summary, evidence, url }
Summaries are short excerpts; follow url for the full release notes.