Developer's Blockchain Reconciliation Tool Caught Five Bugs in Its Own Code First

A developer building an open-source tool called onchain-tieout — designed to verify whether a wallet's reconstructed transaction history matches the balance reported on-chain — discovered the first errors it flagged were in the tool itself. A wrong assumption about Etherscan's pagination limit caused silent data truncation, while a single block containing over 1,000 token transfers exposed a flaw in the cursor logic. Separately, HTTP 429 rate-limit responses were being misclassified as unreadable token contracts, masking network errors as data facts. Two additional bugs were found through manual code review rather than testing, both involving ambiguous inputs being silently converted into plausible but incorrect outputs. When fully corrected and run against vitalik.eth, the tool processed 10,476 balance rows, with 8,281 tying out exactly — most discrepancies traced to airdropped spam contracts.