---
title: "Register Signed Key"
method: POST
path: "/v2/farcaster/auth_address/developer_managed/signed_key/"
tags: ["AuthAddress"]
---

# Register Signed Key

`POST /v2/farcaster/auth_address/developer_managed/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.

## Request body

- RegisterAuthAddressDeveloperManagedSignedKeyReqBody
  - `address` string, required — Ethereum address
  - `app_fid` integer, required — The unique identifier of a farcaster user or app (unsigned integer)
  - `deadline` integer, required — unix timestamp in seconds that controls how long the signed key request is valid for. (24 hours from now is recommended)
  - `redirect_url` string — Url to redirect to after the signer is approved. **Note** : This should only be used when requesting a signer from a native mobile application.
  - `signature` string, required — 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)
  - `sponsor` SignedKeyRequestSponsor
    - `fid` integer — The unique identifier of a farcaster user or app (unsigned integer)
    - `signature` string — Signature generated by the fid of the sponsor and the signature generated from signKeyRequest for the app.
    - `sponsored_by_neynar` boolean — 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.

## Response `200`

Success

- object
  - `address` string, required — Ethereum address
  - `auth_address_approval_url` string, uri
  - `fid` integer — The unique identifier of a farcaster user or app (unsigned integer)
  - `status` 'pending_approval' | 'approved' | 'revoked', required

## Other responses

- `400` — Bad Request
- `500` — Server Error

---

[API](https://skmtc.dev/neynar/apis/neynar-api.md) · [All operations](https://skmtc.dev/neynar/apis/neynar-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/neynar/neynar-api/revisions/dbb91bfb0d1a/schema)