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# Algorand Specifications

The main daemon running in an Algorand Node is called `algod`.

It is responsible for providing access to core blockchain data and functionality. This includes transaction details, account balances, smart contract state, and other node-level information.

The `algod` REST API is used to **GET**:

- Node info (e.g., `/genesis`, `/health`, `/ready`, `/status`, etc.),
- Account info (e.g., `/accounts/{address}`, etc.),
- App info (e.g., `/applications/{application-id}`, etc.),
- ASA info (e.g., `/assets/{asset-id}`, etc.),
- Blocks info (e.g., `/blocks/{round}`, etc.),
- Other ancillary information about the [Ledger](https://specs.algorand.co/ledger/ledger-overview) and pending transactions in the [Transaction Pool](https://specs.algorand.co/ledger/non-normative/ledger-nn-txpool).

The `algod` REST API is used to **POST**:

- Synchronization commands (e.g., `/ledger/sync/{round}`, `/catchup/{catchpoint}`, etc.),
- Transactions (e.g., `/transactions`, `/transactions/simulate`, etc.),
- Consensus commands (e.g., `/participation`, `/participation/generate/{address}`, etc.),
- AVM Compiler commands (e.g., `/teal/compile`, `/teal/disassemble`, etc.),
- Other ancillary dev commands.

> Tasks involving the management and the usage of private keys are handled by a separate daemon, called _Key Management Daemon_ (`kmd`).

Some `algod` endpoints perform sensitive actions that require authorization.

The `X-Algo-API-Token` header is used to authenticate requests to the private `algod` endpoints.

By default, the API can be configured with two separate `X-Algo-API-Token` values:

- The `algod.token` is used to access public `algod` endpoints.
- The `admin.algod.token` is used to access private `algod` endpoints.

Each `algod` endpoint path has two _tags_ to separate endpoints into groups:

- Tag 1: `public` (use the `algod.token`) or private (use `algod.admin.token`),
- Tag 2: `participating`, `nonparticipating`, `data`, or `experimental`.

> Important
> 
> **IMPLEMENTATION:**
> 
> Each endpoint implements a [`Handler`](https://github.com/algorand/go-algorand/blob/cec401cc6127c6af742685e4c39e71389586c595/daemon/algod/api/server/v2/handlers.go) and a [`Client`](https://github.com/algorand/go-algorand/blob/cec401cc6127c6af742685e4c39e71389586c595/daemon/algod/api/client/restClient.go).

The following constants define key limits and default behaviors for various `algod` API endpoints.

These values serve as practical defaults for most use cases. Developers implementing their own tooling or integrations can use these as general guidelines.

| Constant | Value | Description |
| --- | --- | --- |
| `MaxTealSourceBytes` | 524,288 bytes | Maximum allowed size for TEAL source code in API requests. |
| `MaxTealDryrunBytes` | 1,000,000 bytes | Maximum allowed size for dryrun simulation requests. |
| `MaxAssetResults` | 1,000 | Maximum number of assets returned in a single call to `/v2/accounts/{address}/assets`. |
| `DefaultAssetResults` | 1,000 | Default number of assets returned if no explicit limit is provided (up to `MaxAssetResults`). |
| `WaitForBlockTimeout` | 1e+10 nanoseconds (1 min.) | Timeout duration for the `WaitForBlock` endpoint when waiting for the next block to be generated.