> ## Documentation Index > Fetch the complete documentation index at: https://docs.neynar.com/llms.txt > Use this file to discover all available pages before exploring further. # Register Signed Key > Allow apps to register an Ethereum addresses as authorized "auth addresses" for a user's Farcaster account, enabling seamless Sign-In With Farcaster (SIWF) across applications without repeated custody wallet authorizations. ## Node.js SDK 🔗 **SDK Method:** [registerSignedKeyForDeveloperManagedAuthAddress](/nodejs-sdk/auth-addres-apis/registerSignedKeyForDeveloperManagedAuthAddress) Use this API endpoint with the Neynar Node.js SDK for typed responses and better developer experience. ## OpenAPI ````yaml post /v2/farcaster/auth_address/developer_managed/signed_key/ openapi: 3.0.4 info: contact: email: team@neynar.com name: Neynar url: https://neynar.com/ description: >- The Neynar API allows you to interact with the Farcaster protocol among other things. See the [Neynar docs](https://docs.neynar.com/reference) for more details. title: Neynar API version: 3.173.0 servers: - url: https://api.neynar.com security: - ApiKeyAuth: [] tags: - description: Operations related to user externalDocs: description: More info about user url: https://docs.neynar.com/reference/user-operations name: User - description: Operations related to signer externalDocs: description: More info about signer url: https://docs.neynar.com/reference/signer-operations name: Signer - description: Operations related to cast externalDocs: description: More info about cast url: https://docs.neynar.com/reference/cast-operations name: Cast - description: Operations related to feed externalDocs: description: More info about feed url: https://docs.neynar.com/reference/feed-operations name: Feed - description: Operations related to reaction externalDocs: description: More info about reaction url: https://docs.neynar.com/reference/reaction-operations name: Reaction - description: Operations related to notifications externalDocs: description: More info about notifications url: https://docs.neynar.com/reference/notifications-operations name: Notifications - description: Operations related to channels externalDocs: description: More info about channels url: https://docs.neynar.com/reference/channel-operations name: Channel - description: Operations related to follows externalDocs: description: More info about follows url: https://docs.neynar.com/reference/follows-operations name: Follows - description: Operations related to storage externalDocs: description: More info about storage url: https://docs.neynar.com/reference/storage-operations name: Storage - description: Operations related to mini apps name: Frame - description: Operations for building AI agents name: Agents - description: Operations related to fname name: fname - description: Operations related to a webhook name: Webhook - description: >- Securely communicate and perform actions on behalf of users across different apps externalDocs: description: More info about farcaster actions url: https://docs.neynar.com/docs/farcaster-actions-spec name: Action - description: Operations related to a subscriptions name: Subscribers - description: Operations related to a mute name: Mute - description: Operations related to a block name: Block - description: Operations related to a ban name: Ban - description: Operations related to onchain data name: Onchain - description: Operations related to login name: Login - description: Operations related to retrieving metrics name: Metrics - description: Operations related to mini app host notifications externalDocs: description: More info about mini app host notifications url: https://docs.neynar.com/docs/app-host-notifications name: App Host paths: /v2/farcaster/auth_address/developer_managed/signed_key/: post: tags: - AuthAddress summary: Register Signed Key description: >- Allow apps to register an Ethereum addresses as authorized "auth addresses" for a user's Farcaster account, enabling seamless Sign-In With Farcaster (SIWF) across applications without repeated custody wallet authorizations. operationId: register-signed-key-for-developer-managed-auth-address requestBody: content: application/json: schema: $ref: >- #/components/schemas/RegisterAuthAddressDeveloperManagedSignedKeyReqBody required: true responses: '200': content: application/json: schema: properties: address: $ref: '#/components/schemas/EthAddress' auth_address_approval_url: format: uri type: string fid: $ref: '#/components/schemas/Fid' status: enum: - pending_approval - approved - revoked type: string required: - address - status type: object description: Success '400': content: application/json: schema: $ref: '#/components/schemas/ErrorRes' description: Bad Request '500': content: application/json: schema: $ref: '#/components/schemas/ErrorRes' description: Server Error externalDocs: url: >- https://docs.neynar.com/reference/register-signed-key-for-developer-managed-auth-address components: schemas: RegisterAuthAddressDeveloperManagedSignedKeyReqBody: properties: address: $ref: '#/components/schemas/EthAddress' app_fid: $ref: '#/components/schemas/Fid' deadline: description: >- unix timestamp in seconds that controls how long the signed key request is valid for. (24 hours from now is recommended) type: integer redirect_url: description: >- Url to redirect to after the signer is approved. **Note** : This should only be used when requesting a signer from a native mobile application. type: string signature: description: >- Signature generated by the custody address of the app. Signed data includes app_fid, deadline, 32 bytes padded auth address. [Refer guide for more details.](https://docs.neynar.com/docs/auth-address-signature-generation) example: >- 0x16161933625ac90b7201625bfea0d816de0449ea1802d97a38c53eef3c9c0c424fefbc5c6fb5eabe3d4f161a36d18cda585cff7e77c677c5d34a9c87e68ede011c pattern: ^0x[a-fA-F0-9]+$ type: string sponsor: $ref: '#/components/schemas/SignedKeyRequestSponsor' required: - address - app_fid - deadline - signature title: RegisterAuthAddressDeveloperManagedSignedKeyReqBody type: object EthAddress: description: Ethereum address example: '0x5a927ac639636e534b678e81768ca19e2c6280b7' pattern: ^0x[a-fA-F0-9]{40}$ title: EthAddress type: string Fid: description: The unique identifier of a farcaster user or app (unsigned integer) example: 3 format: int32 minimum: 0 title: Fid type: integer ErrorRes: description: Details for the error response properties: code: type: string message: type: string property: type: string status: format: int32 type: integer required: - message title: ErrorRes type: object SignedKeyRequestSponsor: properties: fid: $ref: '#/components/schemas/Fid' signature: description: >- Signature generated by the fid of the sponsor and the signature generated from signKeyRequest for the app. type: string sponsored_by_neynar: description: >- Neynar will sponsor the signer if set to true. **Note: ** If sponsor.fid and sponsor.signature are provided along with sponsored_by_neynar set to true, the sponsor.fid and sponsor.signature will be ignored. Neynar will sponsor the signer on behalf of the user. The developer will get charged in credits. type: boolean title: SignedKeyRequestSponsor type: object securitySchemes: ApiKeyAuth: description: API key to authorize requests in: header name: x-api-key type: apiKey x-default: NEYNAR_API_DOCS ````