ExactOnce – API for actions that can only happen once

Show HN: ExactOnce – API for actions that can only happen once

ExactOnce – API for actions that can only happen once is a business in show hn launch.

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I kept rebuilding the same pattern across products (idempotency keys, Redis TTLs, unique constraints) just to avoid duplicate side effects from retries and race conditions. Eventually I turned it into a focused API.ExactOnce lets you create an action and consume it exactly once. The transition from active → consumed is enforced atomically via a DynamoDB conditional write. Under concurrency, one request succeeds; the rest deterministically get a typed 409 already_used. No distributed locks, no cross-service transactions.Use cases:+ magic login links + coupon redemption + webhook deduplication + one-time download links + ticket scanning + license activationTry it without signing up:curl --requ

Within the show hn launch space, the company focuses on its core offering rather than a broad product line.

Its current recorded stage is Show HN launch.

Website: exactonce.com