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Common mistakes

Twelve real integration failures, each a support ticket we do not want.

  1. Parsing amounts as floats or JSON numbers. They are strings. Always.
  2. Hardcoding 6 decimals. USDT/USDC on BSC are 18.
  3. Re-serializing the body before HMAC. Use the raw bytes.
  4. Trusting the payload before verifying the signature. Verify first.
  5. Not deduping on event.id. Delivery is at-least-once.
  6. Assuming event order. Order on sequence.
  7. Treating deposit.detected as money. Only confirmed is.
  8. Ignoring deposit.orphaned. Reorgs are rare, not impossible, and unhandled they leave your ledger permanently wrong.
  9. Omitting the TON memo. Funds sent without it cannot be attributed.
  10. Retrying a payout without an Idempotency-Key. That is how you pay twice.
  11. Polling instead of subscribing. Webhooks are immediate; polling burns your rate limit.
  12. Doing work before returning 2xx. Ack, then process.

Test mode

What mptest keys can and cannot rehearse.

Going live

Key hygiene, the IP allowlist, signing, and the checklist to walk before real money moves.