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

# sendTransaction (Sender)

> Ultra-low latency transaction submission with multi-path routing across Helius, Jito, Harmonic, Rakurai, and more.

## Request Parameters

<ParamField body="swqos_only" type="boolean" default="false">
  When true, routes exclusively through SWQOS infrastructure, but has a lower minimal tip requirement.
</ParamField>

<ParamField body="transaction" type="string" required>
  The transaction encoded in base64.
</ParamField>

<ParamField body="encoding" type="string">
  Data encoding format used for the Solana transaction payload.

  * `base58`
  * `base64`
</ParamField>

<ParamField body="skipPreflight" type="boolean" default="false">
  When true, bypasses Solana's preflight transaction validation for faster submission. Optional — Sender supports preflight checks.
</ParamField>

<ParamField body="maxRetries" type="number">
  Maximum number of automatic retry attempts. Should be set to 0.
</ParamField>


## OpenAPI

````yaml openapi/sender-api/sendTransaction.yaml POST /fast
openapi: 3.1.0
info:
  title: Helius Sender API
  version: 1.0.0
  description: >-
    Ultra-low latency Solana transaction submission with multi-path routing
    across Helius, Jito, Harmonic, Rakurai, and more.
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0.html
servers:
  - url: https://sender.helius-rpc.com
    description: Global HTTPS endpoint (for frontend applications)
  - url: http://slc-sender.helius-rpc.com
    description: Salt Lake City
  - url: http://ewr-sender.helius-rpc.com
    description: Newark
  - url: http://lon-sender.helius-rpc.com
    description: London
  - url: http://fra-sender.helius-rpc.com
    description: Frankfurt
  - url: http://ams-sender.helius-rpc.com
    description: Amsterdam
  - url: http://sg-sender.helius-rpc.com
    description: Singapore
  - url: http://tyo-sender.helius-rpc.com
    description: Tokyo
security: []
paths:
  /fast:
    post:
      tags:
        - Sender
      summary: sendTransaction
      description: >
        Submit transactions via Helius Sender for ultra-low latency transaction
        submission with multi-path routing across Helius, Jito, Harmonic,
        Rakurai, and more.
      operationId: sendTransaction
      parameters:
        - name: api-key
          in: query
          required: false
          schema:
            type: string
          description: >-
            Standard users do not require an API key. Only users with custom TPS
            limits need to provide an API key.
        - name: swqos_only
          in: query
          required: false
          schema:
            type: boolean
            default: false
          description: >-
            When true, routes exclusively through SWQOS infrastructure, but has
            a lower minimal tip requirement.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                jsonrpc:
                  type: string
                  enum:
                    - '2.0'
                  description: The JSON-RPC protocol version.
                  example: '2.0'
                  default: '2.0'
                id:
                  type: string
                  description: A unique identifier for the request.
                  example: '1'
                  default: '1'
                method:
                  type: string
                  enum:
                    - sendTransaction
                  description: The name of the RPC method to invoke.
                  example: sendTransaction
                  default: sendTransaction
                params:
                  type: array
                  description: Parameters for sending a transaction via Sender.
                  items:
                    oneOf:
                      - type: string
                        description: The transaction encoded in base64.
                      - type: object
                        description: Configuration options for transaction submission.
                        properties:
                          encoding:
                            type: string
                            description: >-
                              Data encoding format used for the Solana
                              transaction payload.
                            enum:
                              - base58
                              - base64
                            example: base64
                          skipPreflight:
                            type: boolean
                            description: >-
                              When true, bypasses Solana's preflight transaction
                              validation for faster submission. Optional —
                              Sender supports preflight checks.
                            example: false
                          maxRetries:
                            type: integer
                            description: >-
                              Maximum number of automatic retry attempts. Should
                              be set to 0.
                            example: 0
            example:
              jsonrpc: '2.0'
              id: '1'
              method: sendTransaction
              params:
                - >-
                  Ab/WBgJxCprwWlK2fCxSwm9KrWlJQW8TdnYqXMvg5KropeLqHaa5yJeoWUb+LsGi6zlfs1Z/jA/RgJW++tBhPAKAAQACBGuePYZrXq9Jj+DwkquiMvsrNU5rlcAbmRfuAYui/CwAQr437DqfrFoSt1BSgM/2/0Iqja1QMefnu1hTYX96AA0DBkZv5SEXMv/srbpyw5vnvIzlu8X3EmssQ5s6QAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAhWHa4WfUT12o+cyi2WGwfBvngyurXf5VQd4Ukn+5ZSIDAgAFAqCGAQACAAkDQA0DAAAAAAADAgABDAIAAABAQg8AAAAAAAA=
                - encoding: base64
                  skipPreflight: true
                  maxRetries: 0
      responses:
        '200':
          description: >-
            Transaction submitted successfully. A 200 response does not
            guarantee that the transaction is valid or that it will land
            onchain.
          content:
            application/json:
              schema:
                type: object
                properties:
                  jsonrpc:
                    type: string
                    description: The JSON-RPC protocol version.
                    enum:
                      - '2.0'
                    example: '2.0'
                  id:
                    type: string
                    description: Identifier matching the request.
                    example: '1'
                  result:
                    type: string
                    description: >-
                      The transaction signature for tracking confirmation
                      status.
                    example: >-
                      4qTLpN1sBrp5SzZUKfrSH2897FmxA7AB4EbN4ccgSgEjG9RG2686pSKWhEbz65q4bvaRsdpKRJKZ3dkdGZA78u5s
              example:
                jsonrpc: '2.0'
                id: '1'
                result: >-
                  4qTLpN1sBrp5SzZUKfrSH2897FmxA7AB4EbN4ccgSgEjG9RG2686pSKWhEbz65q4bvaRsdpKRJKZ3dkdGZA78u5s
        '400':
          description: >-
            Bad Request - Missing tip, priority fee, or invalid submission
            parameters.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                jsonrpc: '2.0'
                error:
                  code: -32602
                  message: Invalid request
                id: '1'
        '429':
          description: Too Many Requests - Rate limit exceeded.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                jsonrpc: '2.0'
                error:
                  code: -32005
                  message: Too many requests
                id: '1'
        '500':
          description: Internal Server Error - An error occurred on the server.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                jsonrpc: '2.0'
                error:
                  code: -32603
                  message: Internal error
                id: '1'
        '503':
          description: Service Unavailable - The service is temporarily unavailable.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                jsonrpc: '2.0'
                error:
                  code: -32002
                  message: Service unavailable
                id: '1'
        '504':
          description: Gateway Timeout - The request timed out.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                jsonrpc: '2.0'
                error:
                  code: -32003
                  message: Gateway timeout
                id: '1'
components:
  schemas:
    ErrorResponse:
      type: object
      properties:
        jsonrpc:
          type: string
          description: The JSON-RPC protocol version.
          enum:
            - '2.0'
          example: '2.0'
        error:
          type: object
          properties:
            code:
              type: integer
              description: The error code.
              example: -32602
            message:
              type: string
              description: The error message.
            data:
              type: object
              description: Additional data about the error.
        id:
          type: string
          description: Identifier matching the request.
          example: '1'

````