| title | API hardening before a partner integration deadline | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| summary | Tightened authentication, rate limits, and contract tests on public-facing APIs so a flagship integration shipped on schedule without a security gamble. | |||||||||||||||
| published | true | |||||||||||||||
| featured | true | |||||||||||||||
| client | Mid-market platform (anonymized) | |||||||||||||||
| stack |
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| metrics |
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A revenue-critical partner integration required exposing stable APIs under a fixed launch date. The existing endpoints “worked in production” for internal callers but were not yet fit for third-party coupling: auth story was inconsistent, error shapes varied, and there was little confidence about burst behavior.
- Clock: immovable marketing/commercial deadline; scope had to be negotiated, not fantasized away.
- Security bar: external tokens, replay considerations, and least-privilege access were non-negotiable.
- Backwards compatibility: internal consumers could not be broken silently while external contracts froze.
We treated the integration surface as a versioned contract:
- explicit auth boundary (short-lived credentials, rotation story documented)
- consistent error envelope and idempotency keys on mutating routes
- OpenAPI (or equivalent) as the shared truth, consumed by contract tests in CI
- separate rate-limit and WAF-adjacent policies for partner traffic classes
Internally, the service layer was refactored so “business operation” endpoints were not duplicated across “internal vs external” paths unless necessary—one implementation, multiple adapters where behaviors diverged.
- Strict compatibility vs velocity: froze v1 behaviors with documented exceptions rather than infinite flexibility—partners need predictability more than novelty.
- Sync vs async flows: chose synchronous request/response where partner mental model demanded simplicity; deferred webhook reliability enhancements to a fast-follow with clear SLAs.
- Load testing scope: focused on partner-shaped traffic mixes, not vanity peak numbers—validated tail latency under practical concurrency.
- Launch proceeded without emergency firewalling or key rotation scrambles.
- Contract tests caught breaking changes pre-merge, reducing integration ping-pong.
- Support load stayed manageable because failure modes were explicit and documented.
I would push earlier for a shared sandbox environment and deterministic test accounts—integration partners always test in ways you did not imagine. Also: publish SLAs for error rates and maintenance windows at the same time as the API docs; ambiguity becomes incidents later.