> ## Documentation Index > Fetch the complete documentation index at: https://docs.beaconcha.in/llms.txt > Use this file to discover all available pages before exploring further. # BLS-to-execution credential changes > Retrieve on-chain BLS-to-execution credential change messages (EIP-4881 style) for one or more validators. Each item includes the slot and epoch of inclusion, the canonical block root, the validator’s BLS pubkey and signature over the change message, the original 0x00 withdrawal credentials, and the resulting 0x01 credentials (derived from the execution address). Provide validator identifiers as a comma-separated list in the path. The service accepts validator indices and 0x-prefixed BLS pubkeys (up to the server-enforced limit; default 100). If a provided pubkey does not resolve to a known validator index, the request fails with HTTP 400. ## OpenAPI ````yaml /api/v1/bundled.yaml get /api/v1/validator/{indexOrPubkey}/blsChange openapi: 3.0.4 info: title: beaconcha.in API Documentation license: name: GPL-3.0 url: https://www.gnu.org/licenses/gpl-3.0.en.html description: >- > ⚠️ No new features or endpoints will be added to V1. We recommend the [V2 API](/api/overview) for all new projects. See the [migration guide](/api/v1-to-v2-migration). ## Introduction **Advanced and reliable API for accessing comprehensive Ethereum blockchain data.** - **Free Usage Policy:** The API is free to use under a fair use policy, with rate limits of 10 requests per minute per IP. - **Caching:** All responses are cached for 1 minute. - **Higher Usage Plans:** For higher usage plans, visit: [https://beaconcha.in/pricing](https://beaconcha.in/pricing). An API key is required to use these plans. ### API Key Usage API keys can be obtained at [/user/settings](https://beaconcha.in/user/settings) and must be included in requests either as a query string parameter or in the request header. #### Example: Query String Parameter ```bash curl https://beaconcha.in/api/v1/slot/1?apikey= ``` #### Example: Request Header ```bash curl -H 'apikey: ' https://beaconcha.in/api/v1/slot/1 ``` contact: {} version: '1.1' servers: - url: https://beaconcha.in description: Ethereum mainnet - url: https://hoodi.beaconcha.in description: Hoodi Ethereum testnet security: - ApiKeyAuthQuery: [] - ApiKeyAuthHeader: [] tags: - name: Epoch description: Data related to consensus layer epochs - name: Slots description: Data related to consensus layer slots - name: Validators description: Data related to consensus layer validators - name: Rewards description: Data related to validator rewards - name: Sync Committees description: Data related to sync committees - name: Rocketpool description: Data related to the rocketpool protocol - name: ETH.Store® description: Data related to the ETH.Store® metric - name: Validator deposits description: Data related to execution layer validator deposits - name: Blocks description: Data related to execution layer blocks - name: Gas description: Data related to gas prices - name: Address description: Data related to ethereum addresses - name: Network description: Network data - name: Misc description: Miscellaneous data - name: User description: User data - name: Machine Metrics description: Submit machine, beacon-node, and validator-client monitoring metrics paths: /api/v1/validator/{indexOrPubkey}/blsChange: get: tags: - Validators summary: BLS-to-execution credential changes description: >- Retrieve on-chain BLS-to-execution credential change messages (EIP-4881 style) for one or more validators. Each item includes the slot and epoch of inclusion, the canonical block root, the validator’s BLS pubkey and signature over the change message, the original 0x00 withdrawal credentials, and the resulting 0x01 credentials (derived from the execution address). Provide validator identifiers as a comma-separated list in the path. The service accepts validator indices and 0x-prefixed BLS pubkeys (up to the server-enforced limit; default 100). If a provided pubkey does not resolve to a known validator index, the request fails with HTTP 400. operationId: listValidatorBlsChanges parameters: - name: indexOrPubkey in: path description: >- Comma-separated validator indices and/or public keys (maximum 100 items by default). required: true style: simple explode: false schema: $ref: '#/components/schemas/primitives.indicesOrPubkeys' responses: '200': description: >- Matching BLS credential changes were retrieved successfully. The `data` array contains one entry per observed change event. content: application/json: schema: allOf: - $ref: '#/components/schemas/types.ApiResponse' - type: object properties: data: type: array items: $ref: >- #/components/schemas/types.ApiValidatorBlsChangeResponse '400': description: >- The request is invalid (for example, malformed identifiers, too many identifiers, unresolved pubkeys, or database error). content: application/json: schema: $ref: '#/components/schemas/types.ApiErrorResponse' examples: invalidParam: summary: Invalid validator identifier value: status: 'ERROR: invalid validator-parameter' data: null tooMany: summary: Too many identifiers value: status: 'ERROR: only a maximum of 100 query parameters are allowed' data: null unresolvedPubkeys: summary: Pubkey did not resolve to an index value: status: >- ERROR: invalid validator argument, pubkey(s) did not resolve to a validator index data: null empty: summary: No or invalid indices provided value: status: 'ERROR: no or invalid validator indicies provided' data: null dbError: summary: Database retrieval error value: status: 'ERROR: could not retrieve db results' data: null '500': description: An unexpected server error occurred while processing your request. content: application/json: schema: $ref: '#/components/schemas/types.ApiErrorResponse' examples: serverError: summary: Internal error value: status: 'ERROR: internal server error' data: null components: schemas: primitives.indicesOrPubkeys: type: string description: > Comma-separated list (no spaces) of validator identifiers. Each identifier must be either: - A validator index as a base-10 integer (for example, 652648) - A BLS public key as a 96-hex-character string with or without the 0x prefix (case-insensitive) Resolution and limits: - The server resolves public keys to validator indices before querying data. - The total number of identifiers must not exceed the server-enforced limit (default 100). - Identifiers that cannot be parsed or resolved result in HTTP 400. example: 1,2,3 types.ApiResponse: type: object description: Standard success envelope used by all API endpoints. properties: status: type: string description: >- HTTP-independent status of the API operation. For successful responses this is always "OK". enum: - OK data: description: Response payload specific to the endpoint. nullable: true x-omitempty: true types.ApiValidatorBlsChangeResponse: type: object description: >- On-chain record of a validator’s BLS-to-execution credential change. Includes consensus-layer inclusion metadata, the validator’s BLS pubkey and signature over the change message, the original 0x00 withdrawal credentials, and the new 0x01 credentials derived from the execution address. properties: epoch: type: integer description: >- Epoch containing the block that included the credential change (>= 0). minimum: 0 example: 200820 slot: type: integer description: >- Slot number of the beacon block that included the credential change (>= 0). minimum: 0 example: 6426248 blockroot: type: string description: 0x-prefixed 32-byte root of the including beacon block. pattern: ^0x[a-fA-F0-9]{64}$ example: '0x387e15e80bfce46c2217cd149ec0a03a5f82ce393de12936ca243e076517148b' validatorindex: type: integer description: Index of the validator that submitted the credential change (>= 0). minimum: 0 example: 20 bls_pubkey: type: string description: >- BLS12-381 validator public key (48 bytes; 0x-prefixed hex with 96 hex characters). pattern: ^0x[a-fA-F0-9]{96}$ example: >- 0x8b84918f955498cd0f6f44537cd0745d29ceffe16a37a353da746ad6879ec1c5992520708aad13b2333ce562faef083c bls_signature: type: string description: >- BLS signature over the change message (96 bytes; 0x-prefixed hex with 192 hex characters). pattern: ^0x[a-fA-F0-9]{192}$ example: >- 0xb735398d821c5eb6356c71e35d59dd29ee56429d03dd443746d3de1bffb9049ed1bd45ab115de42ee3c6d0b69017d9b11413e1c7a0640553c14f8d2076369d51301720f3861c9b824a8a486d116c9bfe38c53747b33d3f1e664ce5ead157ec16 address: type: string description: >- Execution-layer address encoded in the new 0x01 withdrawal credentials (0x-prefixed, 20-byte hex). pattern: ^0x[a-fA-F0-9]{40}$ example: '0x23a64e36ae03d85a6121e55e48f6b8eb63d72f76' withdrawalcredentials_0x00: type: string description: >- Original withdrawal credentials prior to the change (32 bytes; 0x-prefixed hex, starts with 0x00). pattern: ^0x[a-fA-F0-9]{64}$ example: '0x009081da37d4f11d87592b89734db953de64fcb381436b235551b209f3fac343' withdrawalcredentials_0x01: type: string description: >- New withdrawal credentials after the change (32 bytes; 0x-prefixed hex, starts with 0x01 = 0x01 || 0x00..00 || address). pattern: ^0x[a-fA-F0-9]{64}$ example: '0x01000000000000000000000023a64e36ae03d85a6121e55e48f6b8eb63d72f76' types.ApiErrorResponse: type: object description: Standard error envelope returned when a request fails. properties: status: type: string description: >- Human-readable error indicator and message. The value begins with "ERROR:" followed by details. example: 'ERROR: ' data: type: string description: Optional additional context for the error. Null in most cases. nullable: true default: null securitySchemes: ApiKeyAuthQuery: type: apiKey in: query name: apikey description: '' ApiKeyAuthHeader: type: apiKey in: header name: apikey description: '' ````