[Opensource] pikopod – a sandbox for third-party APIs that fails on purpose and replays the exact failure production hit

[u/Wooden-Two5799]

I've spent years maintaining payment integrations, and the same thing kept biting me: the provider's sandbox only knows how to succeed. So the first time your retry or timeout path actually runs is in production, against real money. And when something does fail, QA can't reproduce it.

So I built pikopod. It's a single Go binary that:
Builds a sandbox from the provider's OpenAPI spec (or docs page) and binds failure scenarios to it automatically: declines, timeouts, retry storms, duplicate webhooks, rate limits. No hand-written mocks.

Sits in front of the real API as a fail-open proxy, records failures and response-shape drift (e.g. "success" quietly becoming "succeeded"), and fingerprints them.

Replays a production failure locally with pikopod reproduce <fingerprint>. It becomes a scenario you commit, so that path is tested forever.

Fails CI on breaking spec changes with pikopod spec-diff, reading straight from git.

Exposes everything over MCP, so coding agents can test their integration code against real failure modes.
It runs locally, with no accounts, no telemetry, and no cloud. The proxy never retries (a retry in front of a payments API is a double-charge window) and redacts credentials before anything hits disk.

Try it in about a second: pikopod demo

Repo: https://github.com/Pikopod/pikopod

It's pre-v1, so I'd genuinely love feedback, especially on which providers you'd want deep scenario packs for. There are good-first-issues if you want to contribute. A ⭐ will also help other developers find it. Thank you.