Networks drop requests between 'sent' and 'confirmed'. If 'charge this card' is retried by a timeout, a user clicking twice, or a queue redelivering a message, a non-idempotent endpoint charges twice. The standard fix is an idempotency key: the client sends a unique token per logical operation and the server answers a repeat with the stored first result instead of performing it again.
Where it matters most is exactly where failure is most expensive — payment capture, order creation, webhook handlers, automation steps that send emails or move money. Designing the write paths to be idempotent turns 'retry on failure' from a risk into the normal way flaky infrastructure is survived.
Related terms
CI/CD
Automatically building and testing every change, and automatically shipping the ones that pass.
Static generation (SSG)
Rendering pages to HTML at build time, so a request is answered by handing over a file instead of running code.
n8n
An open-source workflow-automation tool that connects apps, APIs and AI models into repeatable pipelines — self-hostable, so data can stay on your own infrastructure.
The bench this belongs to
Full-stackIf you can describe it, we can build it. React and Next.js on the front, Python or Node behind, Postgres underneath, shipped to somewhere you can afford to run.
