Verification

Source code verification proves that the code deployed at a contract address matches the local Tolk source in the current Acton project. Acton handles the full verifier flow: it compiles the contract, uploads the sources to the TON Verifier backend, collects signatures, and can send the final verification transaction.

This guide covers verification for deployed contracts on testnet and mainnet.

Before verification

Prepare these inputs before running acton verify:

a wallet configured in Acton or a TON Connect wallet
a deployed .tolk contract that is defined in Acton.toml
enough GRAM on the wallet to cover the final verification transaction when not using --dry-run; Acton sends 0.1 GRAM plus normal wallet/network fees

Only Tolk contracts can be verified. Arbitrary .boc contracts are not supported by the verifier flow.

Verification fails if the current local sources do not compile to the same bytecode as the deployed contract. Run verification from the same source revision and compiler configuration used for deployment.

Verify on testnet

Run acton verify with the contract name from Acton.toml and the deployed address:

acton verify Counter --address EQDt7LL...

testnet is the default network, so --net testnet is optional.

If the project defines only one contract, the contract name can be omitted. If multiple contracts are available, Acton prompts for the selection. If --address is omitted, Acton prompts for the address.

On success, Acton prints a verifier link for the contract:

terminal

✓ Contract verification completed!
View at: https://verifier.ton.org/EQBUSJ...?testnet

Verify on mainnet

Pass --net mainnet to target a mainnet deployment:

acton verify Counter --address UQDt7LL... --net mainnet

Choose the wallet for the verification transaction

When more than one wallet is configured, use --wallet to pick the sender for the final verification transaction:

acton verify Counter --address EQDt7LL... --wallet deployer

If exactly one wallet is configured, Acton selects it automatically. If multiple wallets are available and --wallet is omitted, Acton prompts for the selection.

When --dry-run is not used, the final verification transaction sends 0.1 GRAM. If the verifier backend reports that the same code hash is already verified, Acton exits successfully without sending another transaction.

Use TON Connect for the verification transaction

Pass --tonconnect to approve the final verification transaction through a TON Connect wallet instead of a wallet from wallets.toml:

acton verify Counter --address EQDt7LL... --net mainnet --tonconnect

Acton starts a local TON Connect page and opens it in the browser. If the default page port is busy, pass --tonconnect-port <PORT>.

Check the verifier flow without sending the transaction

Use --dry-run to run the verifier flow without publishing the final transaction on-chain:

acton verify Counter --address EQDt7LL... --dry-run

--dry-run still compiles the contract, uploads the sources, and collects the required verifier signatures. It skips only the final blockchain transaction.

Use this mode to confirm that the verifier backend accepts the source package before spending GRAM from the wallet.

Pin the compiler version

If the deployed contract was built with a specific Tolk compiler version, pass that version explicitly:

acton verify Counter --address EQDt7LL... --compiler-version <TOLK_VERSION>

Verification compares the deployed code with the bytecode produced from the submitted sources and compiler settings. A different compiler version can produce a different result even when the source files are unchanged.

Troubleshoot verification failures

A bytecode mismatch usually means that the local sources, imports, or compiler settings differ from the deployment inputs.

Common causes include:

a different Git revision than the one used for deployment
a different Tolk compiler version
changed generated or imported source files
verifying the wrong contract name or address

For backend diagnostics, rerun the command with ACTON_VERIFY_DEBUG=1:

ACTON_VERIFY_DEBUG=1 \
acton verify Counter --address EQDt7LL... --dry-run

With debug mode enabled, Acton prints the compiler version, the collected source files, and any backend overrides.

To test a specific verifier backend, set ACTON_VERIFY_BACKEND:

ACTON_VERIFY_BACKEND=http://127.0.0.1:8080 \
ACTON_VERIFY_DEBUG=1 \
acton verify Counter --address EQDt7LL... --net mainnet --dry-run

To replace the signer backend list, set ACTON_VERIFY_BACKENDS:

ACTON_VERIFY_BACKEND=http://127.0.0.1:8080 \
ACTON_VERIFY_BACKENDS=http://127.0.0.1:8081,http://127.0.0.1:8082 \
acton verify Counter --address EQDt7LL... --net mainnet --dry-run

If the backend returns a transient 5xx error, retry the command. Acton automatically retries source upload failures before exiting.