Validity Transaction Builder
GET https://402.com.tr/api/x402/validity-build
Wrap ANY signed Base transaction (transfer, approve, contract call) in a Cobalt validity transaction: Base holds it dormant until your conditions hold, then includes it — a good-till-block/conditional order, no limit-order contract, nobody holding it. We validate the predicates and return the base_sendRawTransactionValidity request; we never touch funds or keys. Conditions: beforeBlock, fromBlock, flashblockIndex, minNativeBalanceWei, or a storage predicate for price. One required.
How to buy
This endpoint takes pay-per-call payments over x402. Call it once without paying to see its live price; any x402 client then pays and retries automatically.
curl -i -X GET "https://402.com.tr/api/x402/validity-build"
# HTTP/1.1 402 Payment Required: price, asset and payTo are in the responseRecent checks
| Checked (UTC) | Result | Status | Time | Live price |
|---|---|---|---|---|
| 2026-10-11 11:31 | Valid 402 | 402 | 1338 ms | $0.01 |
| 2026-10-11 07:01 | Valid 402 | 402 | 1260 ms | $0.01 |
| 2026-10-11 02:45 | Valid 402 | 402 | 1338 ms | $0.01 |
| 2026-10-10 22:15 | Valid 402 | 402 | 1353 ms | $0.01 |
Receipts
No test purchases yet. Graded test purchases are next on our list; until then every number here comes from unpaid checks.
What a check proves