> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ton.org/llms.txt
> Use this file to discover all available pages before exploring further.

<AgentInstructions>

## Submitting Feedback

If you encounter incorrect, outdated, or confusing documentation on this page, submit feedback:

POST https://docs.ton.org/feedback

```json
{
  "path": "/ecosystem/api/toncenter/v2/blocks/get-outbound-message-queue-size",
  "feedback": "Description of the issue"
}
```

Only submit feedback when you have something specific and actionable to report.

</AgentInstructions>

# Get outbound message queue size

> Returns the current size of the outbound message queue for each shard. A growing queue indicates network congestion. If the queue is large, transactions may take longer to process. Monitor this to detect network issues.



## OpenAPI

````yaml get /api/v2/getOutMsgQueueSize
openapi: 3.1.1
info:
  title: TON HTTP API C++
  description: >
    This API enables HTTP access to TON blockchain - getting accounts and
    wallets information, looking up blocks and transactions, sending messages to
    the blockchain, calling get methods of smart contracts, and more.


    In addition to REST API, all methods are available through a JSON-RPC
    endpoint  with `method` equal to method name and `params` passed as a
    dictionary.


    The response contains a JSON object, which always has a boolean field `ok`
    and either `error` or `result`. If `ok` equals true, the request was
    successful and the result of the query can be found in the `result` field.
    In case of an unsuccessful request, `ok` equals false and the error is
    explained in the `error`.


    API Key should be sent either as `api_key` query parameter or `X-API-Key`
    header
  version: 2.1.1
servers:
  - url: https://toncenter.com
    description: TON Mainnet
  - url: https://testnet.toncenter.com
    description: TON Testnet
security: []
tags:
  - name: Accounts
    description: Information about accounts
  - name: Transactions
    description: Fetching and locating transactions
  - name: Blocks
    description: Information about blocks
  - name: Run method
    description: Run get-method of smart contracts
  - name: Send
    description: Send data to blockchain
  - name: Utils
    description: Some useful methods
  - name: Configuration
    description: Information about blockchain config
  - name: RPC
    description: JSON-RPC and POST endpoints
paths:
  /api/v2/getOutMsgQueueSize:
    get:
      tags:
        - Blocks
      summary: Get outbound message queue size
      description: >-
        Returns the current size of the outbound message queue for each shard. A
        growing queue indicates network congestion. If the queue is large,
        transactions may take longer to process. Monitor this to detect network
        issues.
      operationId: getOutMsgQueueSize_get
      responses:
        '200':
          description: >-
            Outgoing message queue sizes for all active shards. A growing queue
            indicates network congestion and may cause transaction delays.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/OutMsgQueueSizeResponse'
        '401':
          $ref: '#/components/responses/401'
        '403':
          $ref: '#/components/responses/403'
        '429':
          $ref: '#/components/responses/429'
        '504':
          $ref: '#/components/responses/504'
      security:
        - APIKeyHeader: []
        - APIKeyQuery: []
components:
  schemas:
    OutMsgQueueSizeResponse:
      type: object
      additionalProperties: false
      required:
        - ok
        - result
      properties:
        ok:
          type: boolean
          default: true
          description: >-
            Returns `true` if the request succeeded; otherwise `false`. See the
            `error` field for details.
        result:
          $ref: '#/components/schemas/OutMsgQueueSizes'
        '@extra':
          type: string
          description: >-
            Optional request ID that can be passed in the request and received
            back in the response. Useful for matching async responses.
    OutMsgQueueSizes:
      type: object
      additionalProperties: false
      properties:
        '@type':
          type: string
          enum:
            - blocks.outMsgQueueSizes
          default: blocks.outMsgQueueSizes
          description: >-
            TonLib type identifier for outgoing message queue size responses.
            Refer to the [TonLib type
            reference](/ecosystem/api/toncenter/v2-tonlib-types) for a full
            list.
        shards:
          type: array
          description: >-
            Array of per-shard queue sizes. Each entry contains the shard's
            block identifier and the number of outgoing messages waiting in its
            queue (integer).
          items:
            $ref: '#/components/schemas/OutMsgQueueSize'
        ext_msg_queue_size_limit:
          type: integer
          description: >-
            Maximum allowed external message queue size before new messages are
            rejected.
      required:
        - '@type'
        - shards
        - ext_msg_queue_size_limit
    OutMsgQueueSize:
      type: object
      additionalProperties: false
      properties:
        '@type':
          type: string
          enum:
            - blocks.outMsgQueueSize
          default: blocks.outMsgQueueSize
          description: >-
            TonLib type identifier for per-shard queue size entries. Refer to
            the [TonLib type
            reference](/ecosystem/api/toncenter/v2-tonlib-types) for a full
            list.
        id:
          $ref: '#/components/schemas/TonBlockIdExt'
          description: Full block identifier for the shard.
        size:
          type: integer
          description: Number of outgoing messages waiting in this shard's queue.
      required:
        - '@type'
        - id
        - size
    TonBlockIdExt:
      type: object
      additionalProperties: false
      properties:
        '@type':
          type: string
          enum:
            - ton.blockIdExt
          default: ton.blockIdExt
          description: >-
            TonLib type identifier for full block identifiers. Refer to the
            [TonLib type reference](/ecosystem/api/toncenter/v2-tonlib-types)
            for a full list.
        workchain:
          type: integer
          description: 'Workchain ID: `-1` for masterchain, `0` for basechain.'
        shard:
          type: string
          x-usrv-cpp-type: std::int64_t
          description: >-
            Shard identifier as a signed 64-bit integer string. Masterchain uses
            `-9223372036854775808`.
        seqno:
          type: integer
          description: >-
            Block sequence number within its workchain and shard. For the
            masterchain (workchain `-1`), this equals the global block height.
            For basechain shards (workchain `0`), this is the sequence number
            local to that specific shard, not a global height.
        root_hash:
          $ref: '#/components/schemas/TonHash'
          description: Merkle root hash of the block state tree.
        file_hash:
          $ref: '#/components/schemas/TonHash'
          description: >-
            Hash of the serialized block file. Together with `root_hash`,
            uniquely identifies a block.
      required:
        - '@type'
        - workchain
        - shard
        - seqno
        - root_hash
        - file_hash
      description: >-
        A complete block identifier with cryptographic hashes. Contains
        `workchain`, `shard`, `seqno` (position) plus `root_hash` and
        `file_hash` (verification).
    TonHash:
      type: string
      x-usrv-cpp-type: ton_http::types::ton_hash
      description: >-
        A 256-bit hash value. Accepts either hex format (64 characters) or
        base64 format (44 characters). Used for block hashes, transaction
        hashes, and cryptographic proofs.
  responses:
    '401':
      description: API key does not exist. Check for typos or generate a new key.
      content:
        application/json:
          schema:
            type: object
            additionalProperties: false
            required:
              - ok
              - code
              - error
            properties:
              ok:
                type: boolean
                const: false
                description: Always `false` for error responses.
              code:
                type: integer
                const: 401
                description: HTTP status code `401`.
              error:
                type: string
                enum:
                  - API key does not exist
              '@extra':
                type: string
                description: Extra data passed through from the request.
          example:
            ok: false
            code: 401
            error: API key does not exist
    '403':
      description: >-
        API key is not allowed for this network (e.g. testnet key used on
        mainnet).
      content:
        application/json:
          schema:
            type: object
            additionalProperties: false
            required:
              - ok
              - code
              - error
            properties:
              ok:
                type: boolean
                const: false
                description: Always `false` for error responses.
              code:
                type: integer
                const: 403
                description: HTTP status code `403`.
              error:
                type: string
                enum:
                  - Network not allowed
              '@extra':
                type: string
                description: Extra data passed through from the request.
          example:
            ok: false
            code: 403
            error: Network not allowed
    '429':
      description: >-
        Rate limit exceeded. Back off and retry, or use an API key for higher
        limits.
      content:
        application/json:
          schema:
            type: object
            additionalProperties: false
            required:
              - ok
              - code
              - error
            properties:
              ok:
                type: boolean
                const: false
                description: Always `false` for error responses.
              code:
                type: integer
                const: 429
                description: HTTP status code `429`.
              error:
                type: string
                enum:
                  - Ratelimit exceeded
              '@extra':
                type: string
                description: Extra data passed through from the request.
          example:
            ok: false
            code: 429
            error: Ratelimit exceeded
    '504':
      description: Timeout waiting for liteserver response.
      content:
        application/json:
          schema:
            type: object
            additionalProperties: false
            required:
              - ok
              - code
              - error
            properties:
              ok:
                type: boolean
                const: false
                description: Always `false` for error responses.
              code:
                type: integer
                const: 504
                description: HTTP status code `504`.
              error:
                type: string
                enum:
                  - LITE_SERVER_NETWORK timeout
              '@extra':
                type: string
                description: Extra data passed through from the request.
          example:
            ok: false
            code: 504
            error: LITE_SERVER_NETWORK timeout
  securitySchemes:
    APIKeyHeader:
      type: apiKey
      in: header
      name: X-API-Key
      description: >-
        API key header of the form `X-API-Key: <token>`, where `<token>` is the
        API key. Requests without a key are limited to 1 RPS. Refer to the
        [authentication guide](/ecosystem/api/toncenter/v2-authentication) for
        details.
    APIKeyQuery:
      type: apiKey
      in: query
      name: api_key
      description: >-
        API key query parameter of the form `?api_key=<token>`, where `<token>`
        is the API key. Equivalent to the header method. Refer to the
        [authentication guide](/ecosystem/api/toncenter/v2-authentication) for
        details.

````