---
title: "Update a signature"
method: PUT
path: "/v3/grants/{grant_id}/signatures/{signature_id}"
tags: ["Signatures"]
---

# Update a signature

`PUT /v3/grants/{grant_id}/signatures/{signature_id}`

## Request

- Base URL: `https://api.us.nylas.com`
- URL: `https://api.us.nylas.com/v3/grants/{grant_id}/signatures/{signature_id}`
- Auth: one of:
  - HTTP bearer
  - HTTP bearer

Update the specified signature. You can update the `name`, `body`, or both. The signature ID
does not change.

## Query parameters

- `select` string

## Request body

- object
  - `name` string: Updated label for the signature.
  - `body` string: Updated HTML content for the signature. Maximum 100 KB. Images must use externally hosted URLs (base64 inline images are not supported). Nylas sanitizes the HTML on input to prevent malicious content.

## Response `200`

Signature

- object
  - `request_id` string: The request ID.
  - `data` object: The response object.
    - `id` string: Globally unique identifier for the signature.
    - `grant_id` string: The ID of grant for the connected user.
    - `name` string: A label for the signature (for example, "Work", "Personal", or "Mobile").
    - `body` string: The HTML content of the signature. Images must use externally hosted URLs.
    - `object` string: The type of object.
    - `created_at` integer: Unix timestamp when the signature was created.
    - `updated_at` integer: Unix timestamp when the signature was last modified.

## Other responses

- `400`: Bad Request
- `401`: Unauthorized
- `404`: Not Found
- `429`: Rate limited. The provider or Nylas throttled the request. If a provider throttles a request and says how long to wait, the `Retry-After` header gives that number of seconds. When the header is missing, retry with exponential backoff. See [429 rate limit errors by provider](/docs/api/errors/400-response/#429-rate-limit-errors-by-provider).
- `504`: Provider Failure

## Changes

- **2026-09-26** `763d6b969cd7`: 1 info
  - added the optional property `error/provider_error` to the response with the `429` status

[Operation history](https://skmtc.dev/nylas/apis/nylas-api/changes/v3/grants/:grant_id/signatures/:signature_id/put.md)

---

[API](https://skmtc.dev/nylas/apis/nylas-api.md) - [All operations](https://skmtc.dev/nylas/apis/nylas-api/llms.txt) - [OpenAPI document](https://skmtc.dev/nylas/apis/nylas-api/revisions/7782a3e3ab70?raw)