# txdecode

> Pay-per-call transaction decoder on x402

## What this service does
Turn any Base transaction hash into a human-readable action with normalized asset movements. x402-native: pay $0.005 per call in USDC on Base. No signup, no API keys.

## How to use it
Make an HTTP request to any endpoint. Without payment, you receive HTTP 402 with payment requirements. Pay via the x402 protocol on Base using USDC, then retry with the PAYMENT-SIGNATURE header.

## Guarantees
Non-200 responses are never settled — errors never cost $0.005.

## Endpoints
- [GET /api/v1/decode/{txHash}](https://txdecode.com/api/v1/decode/{txHash}): Decode a confirmed Base transaction into a human-readable action plus normalized asset movements (token, amount, USD value). Add ?verbose=true for the full log/event breakdown. — $0.005 USDC

## Pricing
$0.005 USDC per call. Full table at https://txdecode.com/pricing

## Known limitations
- (internal-eth-possible) Internal native-ETH transfers are invisible — the engine is logs-only. Flagged when tx.to is a contract and tx.value > 0.
- (v4-native-leg-invisible) Uniswap v4 native legs emit no log; reported best-effort from tx.value and the signed swap amounts.
- (v4-pool-tokens-unresolved) A v4 PoolId with no pairable ERC-20 Transfers leaves swap legs with an `unknown` asset (amounts preserved).
- Pre-migration Slipstream pools (legacy CLFactory) are reported as `unknown-v3-style`.
- `tx-pending` (422) is best-effort: free-RPC mempool visibility is not guaranteed; the documented fallback is 404 with a false-negative note.
- NFTs are `not-priced` by design in v1 (distinct from `unpriced`).

## Resources
- OpenAPI: https://txdecode.com/api/openapi.json
- Manifest: https://txdecode.com/.well-known/x402.json
- Documentation: https://txdecode.com/docs
- Extended context: https://txdecode.com/llms-full.txt