{"uid":"cap_sscUX146XoTbITIwShua5","slug":"fletcher-checksum-integrity-checksums-18b5705c","name":"Fletcher Checksum (Integrity Checksums)","description":"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.","url":"https://checksum.openverbs.com/v1/fletcher","method":"POST","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method","bodyType","body"],"properties":{"body":{"type":"object","required":["data"],"properties":{"bits":{"enum":[16,32],"type":"integer","description":"Checksum width in bits. Default 16."},"data":{"type":"string","maxLength":5000000,"description":"Input payload."},"encoding":{"enum":["utf8","hex","base64"],"type":"string","description":"How to decode `data`. Default utf8."}},"additionalProperties":false},"type":{"type":"string","const":"http"},"method":{"enum":["POST"],"type":"string"},"bodyType":{"enum":["json","form-data","text"],"type":"string"}},"additionalProperties":false}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_nrgf0HVaBSxYGD-v1I26C","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes a Fletcher-16 or Fletcher-32 checksum over an input payload for data integrity verification.","exampleAgentPrompt":"Compute a Fletcher-32 checksum over this UTF-8 string so I can verify data integrity: 'Hello, world! This is my payload to checksum.'","exampleUseCases":[{"title":"File transmission integrity check","prompt":"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'."},{"title":"Base64 binary data checksum","prompt":"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."},{"title":"Log integrity verification","prompt":"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'."}],"resultDescription":"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.","failureModes":["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"],"whenToPreferThis":"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.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T00:31:39.058Z","isFirstParty":false}