Does this prove the server deduped?

No. It validates format. Behavior still depends on API implementation.

Are non-UUID keys invalid?

Providers differ. This tool focuses on UUID-shaped keys common in modern APIs.

Idempotency Key Checker

In the same workflow: Webhook Tester and API Response Analyzer.

Idempotency Key Checker

Validate an idempotency key for Idempotency-Key header. APIs use it to avoid duplicate side effects on retries.

Idempotency key

✓

Valid key

UUID v4 format (recommended).

Tip

Send the same key with retries; server returns same response without repeating the action. Use UUID v4 per logical operation.

Related tools

UUID Generator — generate UUID v4 for keys
Retry Simulator — test retries with backoff

Why use Idempotency Key Checker?

POST retries depend on idempotency keys. Validate that your keys look like durable UUIDs (or match your internal format) before you rely on them to deduplicate payments or inventory mutations.

Practical tips

Generate keys client-side for user-visible actions; server-side for pure automation.
Log keys with request IDs when reconciling double charges.
Pair with UUID Generator when bootstrapping new clients.

Common questions

Does this prove the server deduped?: No. It validates format. Behavior still depends on API implementation.
Are non-UUID keys invalid?: Providers differ. This tool focuses on UUID-shaped keys common in modern APIs.

About

Validate Idempotency-Key header format (UUID). Check before POST. Free idempotency key validator.

Related tools

Used together

Next step

After idempotency-key-checker, continue with Webhook Tester to validate the next API or webhook layer.