---
title: "Signature"
description: "Collect a drawn mark as an image data value."
group: "Build forms"
order: 14
type: "reference"
parent: "fields"
keywords:
  - "signature"
  - "canvas"
  - "data URL"
  - "acknowledgement"
updated: "2026-07-14"
---

The signature field collects a drawn mark and stores it as an image data string.

## Validation and storage

A non-empty signature must begin with an image data URL. The built-in renderer provides the drawing control and the response view renders the stored image. Save and resume can persist a signature with the other draft answers.

The field has no type-specific schema options beyond the shared label, description, required state, and visibility conditions, and it can't be prefilled from a URL.

## Add a signature field

In the dashboard, select **Add block** and choose **Signature**.

```ts
const signatureField = {
  id: "signature",
  kind: "signature",
  label: "Sign to confirm",
  required: true,
} as const;
```

<Callout variant="warning" title="A drawn mark isn't a legal conclusion">
  Fillo records the submitted image and the response context. Whether that record satisfies the identity, disclosure, consent, and retention requirements for a particular agreement is your team's call.
</Callout>

## Related

- [Save and resume](/docs/save-and-resume): Preserve in-progress answers before submission.
- [Data retention and deletion](/docs/data-retention): Plan how long signature responses should remain.
- [Custom](/docs/fields/custom): Build a different acknowledgement or signing experience.