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Fletcher Checksum (Integrity Checksums)
x402
Fletcher Checksum (Integrity Checksums) is a paid API for AI agents from checksum.openverbs.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).
Computes a Fletcher-16 or Fletcher-32 checksum over an input payload for data integrity verification.
Price / call$0.002
Success—
StatusUnknown
How this service works
Fletcher checksum over the input payload, in 16-bit (default) or 32-bit width. Returns the checksum as an unsigned integer and hex. Non-cryptographic.
Output
Returns the computed Fletcher checksum value (16-bit or 32-bit integer) for the provided input payload, calculated according to the Fletcher algorithm over the decoded data.
Example use cases
File transmission integrity check
“Before I send this large text payload over the wire, compute a Fletcher-16 checksum over it so the receiver can verify nothing got corrupted in transit: 'ORDER:12345|USER:abc|AMOUNT:99.99|ITEMS:widget,gadget'.”
Base64 binary data checksum
“I have some base64-encoded binary data and I need a Fletcher-32 checksum over it to confirm it hasn't been tampered with — the data is 'SGVsbG8gV29ybGQ=' and the encoding is base64.”
Log integrity verification
“Compute a Fletcher-16 checksum for this UTF-8 log line so I can store the checksum alongside the record and detect future corruption: '2024-01-15T10:23:45Z ERROR service=auth msg=login failed user=jdoe'.”
Technical details
Endpoint
POSThttps://checksum.openverbs.com/v1/fletcherWhen to prefer
Use this endpoint when you need a fast, lightweight, non-cryptographic checksum for error detection — particularly the Fletcher algorithm specifically. Prefer this over CRC or Adler endpoints when your downstream system expects Fletcher-compatible checksums. Suitable for data integrity checks on text, hex, or base64-encoded binary payloads up to 5MB.
Side effects
- Payload exceeds 5MB maximum size — request rejected
- Invalid encoding value (not utf8, hex, or base64) — validation error
- Base64 or hex data that is malformed/unparseable — decoding error
- bits value not 16 or 32 — schema validation failure
- Missing required 'data' field — 400 error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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