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PR-time chaos testing for billing and API failures

Build a narrow-scope PR-time reliability checker aimed at a specific stack (e.g. Stripe-dependent SaaS billing flows, or Postgres+queue apps) that injects failures into third-party dependency calls (Stripe, webhooks, queues) and flags double-charge, duplicate-payout, or lockout bugs before merge. Target indie SaaS founders and small teams using Stripe/billing infra who cannot afford full chaos-engineering setups, selling as a lightweight CI/GitHub Action add-on rather than a full staging-environment clone.

via Hacker News
Original post

What to build

A GitHub Action / CI check that injects simulated failures into third-party dependency calls (Stripe API, webhooks, job queues) against a PR's code, flagging double-charge, duplicate-payout, or account-lockout bugs before merge — built for indie SaaS founders running Stripe-based billing.

A Show HN tool for static reliability-bug detection signals appetite for lightweight, no-staging-environment bug catchers; narrowing that to Stripe/billing failure injection as a pre-merge CI add-on is a focused, sellable wedge.

Demand

Indie SaaS founders and small teams on Stripe who can't justify Gremlin- or Datadog-level chaos engineering setups want a cheap, narrow safety net that catches billing-logic bugs (double charges, duplicate payouts, lockouts) before they hit production.

  • Hacker NewsNews

    Show HN: 'I built a tool that finds reliability bugs in your code' — 6 points, 0 comments. Low engagement, but confirms an active builder shipping in this exact problem space right now.

  • Opportunity analysisAnalysis

    Derived framing suggests the sellable version is a narrow-scope PR-time checker for Stripe-dependent billing flows or Postgres+queue apps, positioned as a lightweight GitHub Action rather than a full chaos-engineering platform.

Stack

  • GitHub Actions
  • Stripe API (test mode) + Stripe CLI webhook simulator
  • Node.js/TypeScript
  • Docker (sandboxed test runner)
  • Postgres
  • BullMQ or similar queue library

Solo + AI difficulty

MVP is buildable solo in 4-6 weeks: a GitHub Action that runs a repo's test suite with Stripe/webhook calls intercepted and failure-injected is straightforward with the Stripe test-mode API and a mock proxy. The hard part is covering enough real-world failure modes (partial webhook delivery, retry races, idempotency-key misuse) accurately enough to avoid high false-positive rates, and keeping pace as Stripe's API evolves.

Entry threshold
Core demo (spin up app copy, proxy third-party calls, inject faults, have an LLM agent infer invariants from the diff) is a non-trivial multi-week build requiring infra orchestration (ephemeral environments, service mocking, traffic proxying) rather than a weekend project, but a narrowed single-dependency version (just Stripe webhook fault injection) is buildable solo with AI coding agents in 2-4 weeks.
Window
6-12 months

Where to find first users

  • Indie Hackers
  • r/SaaS and r/stripe-adjacent developer communities
  • GitHub Marketplace listing
  • Stripe developer Discord/community forums
  • Product Hunt launch

Competitors

Counter-signals & risks

  • Show HN launches often reflect a single builder's narrow personal use case and may not generalize to repeatable commercial demand.

  • Large chaos-engineering and observability vendors (Gremlin, Datadog) could add similar narrow dependency-failure-injection features to their existing platforms, eroding differentiation for a standalone tool.

  • Static or pre-merge failure injection for third-party calls may produce high false-positive rates or require deep per-provider API integration, increasing maintenance burden as billing providers change their APIs.

Original title: Show HN: I built a tool that finds reliability bugs in your code

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PR-time chaos testing for billing and API failures — Nichr