Decoding Solana v0 Transactions with Address Lookup Tables

A robust method for reconstructing account keys and instructions in Solana v0 transactions that use Address Lookup Tables.

Declare the supported version

When calling getTransaction, set maxSupportedTransactionVersion explicitly. Otherwise a client may reject or omit v0 transactions while appearing to work for legacy traffic.

Resolve the complete key space

A v0 message combines static account keys with writable and readonly addresses loaded from one or more ALTs. Reconstruct the runtime order before mapping instruction account indexes.

Use response metadata when available

Loaded addresses in confirmed transaction metadata are the best evidence of the keys used at execution. If resolving tables independently, fetch the correct table state and preserve the slot context.

Cache without assuming immutability

ALTs can be extended and later deactivated. Cache by table address with observed slot and address count, then invalidate when an instruction references an index beyond the cached state or metadata disagrees.

Decode economic effects

After resolving keys, combine top-level and inner instructions with pre/post token balances, SOL balances and fees. Preserve unknown program calls instead of dropping the entire transaction.

Develop a production decoder

TierZero builds Solana data pipelines, wallet analytics and execution bots. Review the official ALT guide or contact us for an implementation.

Production checklist

Before launch, define ownership, test fixtures, failure states, alerts and a rollback procedure. For a scoped engineering review, use the TierZero project form.