Transaction

Transactions in the Concordium blockchain can be any of the following three:

1. Account Creation
2. Account Transaction
3. Update

Account Creation

Whenever a user uses one of the various Concordium Wallets to create a new account, an account_creation transaction is added to a block.

Details of an account creation. These transactions are free, and we only ever get a response for them if the account is created, hence no failure cases.

GRPC documentation: concordium.v2.AccountCreationDetails

Attributes:

Name	Type	Description
credential_type	CredentialType	Whether this is an initial or normal account.
address	CCD_AccountAddress	Address of the newly created account.
reg_id	CCD_CredentialRegistrationId	Credential registration ID of the first credential.

Source code in .venv/lib/python3.13/site-packages/ccdexplorer/grpc_client/CCD_Types/__init__.py

class CCD_AccountCreationDetails(BaseModel):
    """Details of an account creation. These transactions are free, and we only ever get a response for them if the account is created, hence no failure cases.

    GRPC documentation: [concordium.v2.AccountCreationDetails](https://docs.concordium.com/concordium-grpc-api/#concordium.v2.AccountCreationDetails)

    Attributes:
        credential_type (CredentialType): Whether this is an initial or normal account.
        address (CCD_AccountAddress): Address of the newly created account.
        reg_id (CCD_CredentialRegistrationId): Credential registration ID of the first credential.
    """

    credential_type: int
    address: CCD_AccountAddress
    reg_id: CCD_CredentialRegistrationId

Account Transaction

These are user initiated transactions and paid for by the sender. Account transactions can have the following types:

Effects of an account transaction. All variants except None correspond to a unique transaction that was successful.

GRPC documentation: concordium.v2.AccountTransactionEffects

Attributes:

Name	Type	Description
none	Optional[CCD_AccountTransactionEffects_None]	No effects other than payment from this transaction.
module_deployed	Optional[CCD_ModuleRef]	A smart contract module with the attached reference was deployed.
contract_initialized	Optional[CCD_ContractInitializedEvent]	A smart contract was initialized.
contract_update_issued	Optional[CCD_ContractUpdateIssued]	A smart contract instance update was issued.
account_transfer	Optional[CCD_AccountTransfer]	A simple account to account transfer occurred.
baker_added	Optional[CCD_BakerAdded]	A validator was added.
baker_removed	Optional[CCD_BakerId]	A validator was removed.
baker_stake_updated	Optional[CCD_BakerStakeUpdated]	A validator's stake was updated.
baker_restake_earnings_updated	Optional[CCD_BakerEvent_BakerRestakeEarningsUpdated]	A validator's restake earnings setting was updated.
baker_keys_updated	Optional[CCD_BakerKeysEvent]	A validator's keys were updated.
encrypted_amount_transferred	Optional[CCD_AccountTransactionEffects_EncryptedAmountTransferred]	An encrypted amount was transferred.
transferred_to_encrypted	Optional[CCD_EncryptedSelfAmountAddedEvent]	An account transferred part of its public balance to its encrypted balance.
transferred_to_public	Optional[CCD_AccountTransactionEffects_TransferredToPublic]	An account transferred part of its encrypted balance to its public balance.
transferred_with_schedule	Optional[CCD_TransferredWithSchedule]	A transfer with a release schedule was made.
credential_keys_updated	Optional[CCD_CredentialRegistrationId]	Keys of a specific credential were updated.
credentials_updated	Optional[CCD_AccountTransactionEffects_CredentialsUpdated]	Account credentials were updated.
data_registered	Optional[CCD_RegisteredData]	Some data was registered on the chain.
baker_configured	Optional[CCD_BakerConfigured]	A validator was configured.
delegation_configured	Optional[CCD_DelegationConfigured]	A delegator was configured.

Source code in .venv/lib/python3.13/site-packages/ccdexplorer/grpc_client/CCD_Types/__init__.py

class CCD_AccountTransactionEffects(BaseModel):
    """Effects of an account transaction. All variants except `None` correspond to a unique transaction that was successful.

    GRPC documentation: [concordium.v2.AccountTransactionEffects](https://docs.concordium.com/concordium-grpc-api/#concordium.v2.AccountTransactionEffects)

    Attributes:
        none (Optional[CCD_AccountTransactionEffects_None]): No effects other than payment from this transaction.
        module_deployed (Optional[CCD_ModuleRef]): A smart contract module with the attached reference was deployed.
        contract_initialized (Optional[CCD_ContractInitializedEvent]): A smart contract was initialized.
        contract_update_issued (Optional[CCD_ContractUpdateIssued]): A smart contract instance update was issued.
        account_transfer (Optional[CCD_AccountTransfer]): A simple account to account transfer occurred.
        baker_added (Optional[CCD_BakerAdded]): A validator was added.
        baker_removed (Optional[CCD_BakerId]): A validator was removed.
        baker_stake_updated (Optional[CCD_BakerStakeUpdated]): A validator's stake was updated.
        baker_restake_earnings_updated (Optional[CCD_BakerEvent_BakerRestakeEarningsUpdated]): A validator's restake earnings setting was updated.
        baker_keys_updated (Optional[CCD_BakerKeysEvent]): A validator's keys were updated.
        encrypted_amount_transferred (Optional[CCD_AccountTransactionEffects_EncryptedAmountTransferred]): An encrypted amount was transferred.
        transferred_to_encrypted (Optional[CCD_EncryptedSelfAmountAddedEvent]): An account transferred part of its public balance to its encrypted balance.
        transferred_to_public (Optional[CCD_AccountTransactionEffects_TransferredToPublic]): An account transferred part of its encrypted balance to its public balance.
        transferred_with_schedule (Optional[CCD_TransferredWithSchedule]): A transfer with a release schedule was made.
        credential_keys_updated (Optional[CCD_CredentialRegistrationId]): Keys of a specific credential were updated.
        credentials_updated (Optional[CCD_AccountTransactionEffects_CredentialsUpdated]): Account credentials were updated.
        data_registered (Optional[CCD_RegisteredData]): Some data was registered on the chain.
        baker_configured (Optional[CCD_BakerConfigured]): A validator was configured.
        delegation_configured (Optional[CCD_DelegationConfigured]): A delegator was configured.
    """

    none: Optional[CCD_AccountTransactionEffects_None] = None
    module_deployed: Optional[CCD_ModuleRef] = None
    contract_initialized: Optional[CCD_ContractInitializedEvent] = None
    contract_update_issued: Optional[CCD_ContractUpdateIssued] = None
    account_transfer: Optional[CCD_AccountTransfer] = None
    baker_added: Optional[CCD_BakerAdded] = None
    baker_removed: Optional[CCD_BakerId] = None
    baker_stake_updated: Optional[CCD_BakerStakeUpdated] = None
    baker_restake_earnings_updated: Optional[CCD_BakerEvent_BakerRestakeEarningsUpdated] = None
    baker_keys_updated: Optional[CCD_BakerKeysEvent] = None
    encrypted_amount_transferred: Optional[
        CCD_AccountTransactionEffects_EncryptedAmountTransferred
    ] = None
    transferred_to_encrypted: Optional[CCD_EncryptedSelfAmountAddedEvent] = None
    transferred_to_public: Optional[CCD_AccountTransactionEffects_TransferredToPublic] = None
    transferred_with_schedule: Optional[CCD_TransferredWithSchedule] = None
    credential_keys_updated: Optional[CCD_CredentialRegistrationId] = None
    credentials_updated: Optional[CCD_AccountTransactionEffects_CredentialsUpdated] = None
    data_registered: Optional[CCD_RegisteredData] = None
    baker_configured: Optional[CCD_BakerConfigured] = None
    delegation_configured: Optional[CCD_DelegationConfigured] = None
    token_update_effect: Optional[CCD_TokenEffect] = None

Note that for account transactions, we add a recognized_sender_id whenever the sender or invoked contract matches an entry in projects.json.
The lookup happens inside ms_indexers so every document in the transactions collection carries a project_id tag when possible.

Update

Update transactions are performed by the chain itself. The following payloads are possible:

The payload of a chain update.

GRPC documentation: concordium.v2.UpdatePayload

Attributes:

Name	Type	Description
protocol_update	Optional[CCD_ProtocolUpdate]	The protocol version was updated.
election_difficulty_update	Optional[CCD_ElectionDifficulty]	The election difficulty was updated.
euro_per_energy_update	Optional[CCD_ExchangeRate]	The euro per energy exchange rate was updated.
micro_ccd_per_euro_update	Optional[CCD_ExchangeRate]	The microCCD per euro exchange rate was updated.
foundation_account_update	Optional[CCD_AccountAddress]	The foundation account address was updated.
mint_distribution_update	Optional[CCD_MintDistributionCpv0]	The mint distribution was updated (protocol version 1-3).
transaction_fee_distribution_update	Optional[CCD_TransactionFeeDistribution]	The transaction fee distribution was updated.
gas_rewards_update	Optional[CCD_GasRewards]	The gas rewards were updated (protocol version 1-5).
baker_stake_threshold_update	Optional[CCD_BakerStakeThreshold]	The minimum amount of CCD needed to become a validator was updated.
root_update	Optional[CCD_RootUpdate]	The root keys were updated.
level_1_update	Optional[CCD_Level1Update]	The level 1 keys were updated.
add_anonymity_revoker_update	Optional[CCD_ArInfo]	An anonymity revoker was added.
add_identity_provider_update	Optional[CCD_IpInfo]	An identity provider was added.
cooldown_parameters_cpv_1_update	Optional[CCD_CooldownParametersCpv1]	The cooldown parameters were updated.
pool_parameters_cpv_1_update	Optional[CCD_PoolParametersCpv1]	The pool parameters were updated.
time_parameters_cpv_1_update	Optional[CCD_TimeParametersCpv1]	The time parameters were updated.
mint_distribution_cpv_1_update	Optional[CCD_MintDistributionCpv1]	The mint distribution was updated (protocol version 4+).
gas_rewards_cpv_2_update	Optional[CCD_GasRewardsCpv2]	The gas rewards were updated (protocol version 6+).
timeout_parameters_update	Optional[CCD_TimeoutParameters]	The consensus timeouts were updated.
min_block_time_update	Optional[CCD_Duration]	The minimum time between blocks was updated.
block_energy_limit_update	Optional[CCD_Energy]	The block energy limit was updated.
finalization_committee_parameters_update	Optional[CCD_FinalizationCommitteeParameters]	The finalization committee parameters were updated.
validator_score_parameters_update	Optional[CCD_ValidatorScoreParameters]	The validator score parameters were updated.

Source code in .venv/lib/python3.13/site-packages/ccdexplorer/grpc_client/CCD_Types/__init__.py

class CCD_UpdatePayload(BaseModel):
    """The payload of a chain update.

    GRPC documentation: [concordium.v2.UpdatePayload](https://docs.concordium.com/concordium-grpc-api/#concordium.v2.UpdatePayload)

    Attributes:
        protocol_update (Optional[CCD_ProtocolUpdate]): The protocol version was updated.
        election_difficulty_update (Optional[CCD_ElectionDifficulty]): The election difficulty was updated.
        euro_per_energy_update (Optional[CCD_ExchangeRate]): The euro per energy exchange rate was updated.
        micro_ccd_per_euro_update (Optional[CCD_ExchangeRate]): The microCCD per euro exchange rate was updated.
        foundation_account_update (Optional[CCD_AccountAddress]): The foundation account address was updated.
        mint_distribution_update (Optional[CCD_MintDistributionCpv0]): The mint distribution was updated (protocol version 1-3).
        transaction_fee_distribution_update (Optional[CCD_TransactionFeeDistribution]): The transaction fee distribution was updated.
        gas_rewards_update (Optional[CCD_GasRewards]): The gas rewards were updated (protocol version 1-5).
        baker_stake_threshold_update (Optional[CCD_BakerStakeThreshold]): The minimum amount of CCD needed to become a validator was updated.
        root_update (Optional[CCD_RootUpdate]): The root keys were updated.
        level_1_update (Optional[CCD_Level1Update]): The level 1 keys were updated.
        add_anonymity_revoker_update (Optional[CCD_ArInfo]): An anonymity revoker was added.
        add_identity_provider_update (Optional[CCD_IpInfo]): An identity provider was added.
        cooldown_parameters_cpv_1_update (Optional[CCD_CooldownParametersCpv1]): The cooldown parameters were updated.
        pool_parameters_cpv_1_update (Optional[CCD_PoolParametersCpv1]): The pool parameters were updated.
        time_parameters_cpv_1_update (Optional[CCD_TimeParametersCpv1]): The time parameters were updated.
        mint_distribution_cpv_1_update (Optional[CCD_MintDistributionCpv1]): The mint distribution was updated (protocol version 4+).
        gas_rewards_cpv_2_update (Optional[CCD_GasRewardsCpv2]): The gas rewards were updated (protocol version 6+).
        timeout_parameters_update (Optional[CCD_TimeoutParameters]): The consensus timeouts were updated.
        min_block_time_update (Optional[CCD_Duration]): The minimum time between blocks was updated.
        block_energy_limit_update (Optional[CCD_Energy]): The block energy limit was updated.
        finalization_committee_parameters_update (Optional[CCD_FinalizationCommitteeParameters]): The finalization committee parameters were updated.
        validator_score_parameters_update (Optional[CCD_ValidatorScoreParameters]): The validator score parameters were updated.
    """

    protocol_update: Optional[CCD_ProtocolUpdate] = None
    election_difficulty_update: Optional[CCD_ElectionDifficulty] = None
    euro_per_energy_update: Optional[CCD_ExchangeRate] = None
    micro_ccd_per_euro_update: Optional[CCD_ExchangeRate] = None
    foundation_account_update: Optional[CCD_AccountAddress] = None
    mint_distribution_update: Optional[CCD_MintDistributionCpv0] = None
    transaction_fee_distribution_update: Optional[CCD_TransactionFeeDistribution] = None
    baker_stake_threshold_update: Optional[CCD_BakerStakeThreshold] = None
    root_update: Optional[CCD_RootUpdate] = None
    level_1_update: Optional[CCD_Level1Update] = None
    add_anonymity_revoker_update: Optional[CCD_ArInfo] = None
    add_identity_provider_update: Optional[CCD_IpInfo] = None
    cooldown_parameters_cpv_1_update: Optional[CCD_CooldownParametersCpv1] = None
    pool_parameters_cpv_1_update: Optional[CCD_PoolParametersCpv1] = None
    time_parameters_cpv_1_update: Optional[CCD_TimeParametersCpv1] = None
    mint_distribution_cpv_1_update: Optional[CCD_MintDistributionCpv1] = None
    finalization_committee_parameters_update: Optional[CCD_FinalizationCommitteeParameters] = None
    validator_score_parameters_update: Optional[CCD_ValidatorScoreParameters] = None
    create_plt_update: Optional[CCD_CreatePLT] = None

Augmentations performed by CCDExplorer

• ms_events_and_impacts adds impacted_addresses, including canonical address references for alias-safe queries.
• ms_indexers fans out transactions into specialized collections (transactions_transfer, transactions_contracts, etc.) for fast explorer lookups.
• ms_token_accounting reads logged_events emitted by contract_update_issued transactions to update token ledgers.

How is a transaction stored in the system?

heartbeat ingests each block’s transactions and writes them to MongoDB; follow-up workers (listed above) enrich the base documents with project IDs, alias-friendly fields, and derived statistics.***