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How OpenScan Decodes Contract Events with AI

by OpenScan Engineering

Engineering

Every block explorer shows you logs. Almost none of them tell you what happened. “Transfer(address,address,uint256)” with three hex blobs is technically decoded — and practically useless. Here’s how OpenScan’s AI insight engine goes further.

Layer 1: deterministic decoding

First we do what any explorer should: match event signatures against known ABIs, including every verified contract on the chain. For verified contracts this is exact — we use the contract’s own ABI, so parameter names and types are always right.

Layer 2: behavioral inference

For unverified contracts — the majority on any chain — we infer. Token-like Transfer events with 18-decimal amounts and a matching Approval flow? That’s an ERC-20, and the AI insight engine labels it accordingly, with a confidence signal. Swap-shaped event clusters across two token contracts get recognized as DEX activity. This is inference, not magic: we mark inferred decodes so you can always tell them apart from verified ones.

Layer 3: the summary

The final step is compression: turning a transaction’s full trace — calls, events, token movements — into one sentence. “Swapped 1,200 USDC for XDC on a DEX” replaces a wall of internal transactions. That’s the line you see at the top of a transaction page on xdcscan.io.

All three layers ship in every explorer we operate — XDC Network today, with EVS, Wanchain, and Velas on the same stack — and the decoded data is available over the REST API v2 for builders who want it in their own apps.

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Everything we write about here is running today on XDCScan, our explorer for XDC Network.

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