Tokenised carbon credits for an ESG reporting platform

The client operates an ESG and greenhouse-gas reporting platform that produces audit-ready sustainability reports for organisations answering to regulators and the public. In that setting, a report is only as good as the evidence behind it, and auditors expect that evidence to be verifiable rather than asserted.

Carbon credits sat at the heart of those reports, but the record of which credits had been issued and which had been retired was scattered and prone to error, undermining exactly the assurance the platform existed to provide.

Carbon credits can only be counted once: a credit that has been retired to offset emissions must not be able to be double-counted or reused. Tracking that across spreadsheets and disconnected systems left room for exactly the errors that erode an auditor's trust.

Those data errors were not just untidy; they were a credibility risk. If a report's underlying credit records cannot be verified, the whole sustainability claim is open to challenge by auditors and regulators alike.

The platform needed an authoritative, tamper-proof record of credit issuance and retirement that an auditor could inspect directly, so that the reports it produced could withstand scrutiny.

We built carbon-credit issuance and retirement contracts in Solidity, using the ERC-1155 standard to represent credits and enforce that a retired credit is permanently and verifiably taken out of circulation. Making retirement final on-chain is what removes the double-counting risk at its root.

Every issuance and retirement is recorded on-chain, giving auditors a tamper-proof trail they can verify independently rather than taking the platform's word for it. We deployed on Polygon and built with Hardhat, keeping per-transaction cost low enough to record credit events at scale.

Because the authoritative record now lives in the contracts rather than in reconciled spreadsheets, the manual discrepancies that plagued the old process largely disappeared, cutting reporting data errors by 94%. The evidence behind each report became verifiable by construction.