---
title: "Sign and check BizPrint Print API requests with the signing tool"
description: "Use the BizPrint signing tool on the command line to sign a Print API request by hand, or to check why a signature does not match."
url: https://docs.getbizprint.com/developers/signing-tool/
section: "Developers"
last_updated: 2026-11-12
---

# Sign and check BizPrint Print API requests with the signing tool

Section: Developers

> Use the BizPrint signing tool on the command line to sign a Print API request by hand, or to check why a signature does not match.

This page shows you how to use the BizPrint signing tool, a small command-line program published on npm as `@bizswoop/print-sign-request-cli`. It is for developers who call the BizPrint Print API over plain HTTP and want to sign a request by hand, or check a signature that the API rejects.

The tool does the same signing as described in [Sign BizPrint Print API requests](https://docs.getbizprint.com/developers/authentication/). It is a help for testing and debugging. Your own server still signs the requests your app sends. If your server runs Node.js, it can sign them with the SDK. See [Use the BizPrint Node.js SDK to create and check print jobs](https://docs.getbizprint.com/developers/node-sdk/).

## Before you start

- Install Node.js 20.19 or later on your own computer. The tool runs with `npx`, which comes with Node.js.
- Have the [Public Key and Secret Key](https://docs.getbizprint.com/start-here/glossary/#public-key-and-secret-key) of an [application](https://docs.getbizprint.com/start-here/glossary/#application) that uses the **REST API**. See [Get API keys for the BizPrint Print API](https://docs.getbizprint.com/developers/get-api-keys/).
- Run the tool only on a computer you trust. You type the Secret Key into the terminal and it shows on screen. Do not run it while you share your screen, and never paste the Secret Key into a ticket, chat or email.

## Start the tool

1. Open a terminal.

2. Run this command:

   ```sh
   npx @bizswoop/print-sign-request-cli
   ```

3. Confirm the install if `npx` asks. The tool asks **What do you want to do?**

4. Use the arrow keys to choose one of the options.

5. Press Enter.

| Option                      | What it does                                |
| --------------------------- | ------------------------------------------- |
| **Make a get request**      | Signs the query string for a `GET` request. |
| **Make a post request**     | Signs a JSON body for a `POST` request.     |
| **Validate a get request**  | Checks the `hash` in a signed query string. |
| **Validate a post request** | Checks the `hash` in a signed JSON body.    |

## Sign a GET request

1. Choose **Make a get request**.

2. Type your Public Key at **Public key**.

3. Type your Secret Key at **Secret key**.

4. Paste the request address, or only its query string, at **Enter Request URL or query string**. For example:

   ```text
   https://print.bizswoop.app/api/connect-application/v1/printers?perPage=10&page=1
   ```

5. Answer **Update time?** with Yes (the default). The tool sets `time` to the current time.

6. Copy the query string the tool prints. It has your parameters plus `publicKey`, `time` and `hash`.

7. Send the request to the same path with that query string, for example `https://print.bizswoop.app/api/connect-application/v1/printers?` followed by the copied text.

Send the signed request within a few minutes. The API checks `time` and rejects requests that are too old. If you change any parameter after signing, sign it again.

## Sign a POST request

1. Choose **Make a post request**.

2. Type your Public Key at **Public key**.

3. Type your Secret Key at **Secret key**.

4. Answer **Update time?** with Yes (the default).

5. Press Enter at **Enter JSON payload**. Your terminal’s default text editor opens. To use a different editor, set the `EDITOR` environment variable before you start the tool.

6. Type the JSON body, for example:

   ```json
   {
     "printerId": YOUR_PRINTER_ID,
     "url": "https://example.com/receipts/1001.pdf?token=LONG_RANDOM_TOKEN",
     "description": "Order 1001"
   }
   ```

   Replace `YOUR_PRINTER_ID` with the ID of your [printer](https://docs.getbizprint.com/start-here/glossary/#printer), as a number without quotes.

7. Save the file.

8. Close the editor.

9. Copy the JSON the tool prints. It is your body plus `publicKey`, `time` and `hash`.

10. Send it as the body of the `POST` request, exactly as printed, with the header `Content-Type: application/json`.

> **Caution**
>
> Sending a signed `POST /jobs` body creates a new [print job](https://docs.getbizprint.com/start-here/glossary/#print-job) and prints it, every time you send it. Send it once. If you get no answer, do not send it again until you have done all of these checks:
>
> - Look at the paper at the printer for that document.
> - Look up your jobs with the API to see whether the job was created, and check its [status](https://docs.getbizprint.com/start-here/glossary/#print-job-status). See [Check print job status with the BizPrint Print API](https://docs.getbizprint.com/developers/job-status/).
> - Check the job’s status in the [BizPrint dashboard](https://docs.getbizprint.com/start-here/glossary/#bizprint-dashboard).
> - Wait for the [station](https://docs.getbizprint.com/start-here/glossary/#station) to finish anything it is still printing, whatever status the job shows.
>
> Never send it again while the original job is `pending`, `connecting-to-printer` or `processing`.

## Check a signature

Use the validate options when the API answers `ERR_UNAUTHORIZED` and you want to know whether the signature is the problem.

1. Choose **Validate a get request** or **Validate a post request**.
2. Type your Secret Key at **Secret key**.
3. Paste the signed query string or address for a get request, or paste the signed JSON body into the editor for a post request.
4. Save the file, if you used the editor.
5. Close the editor.
6. Read the result.

| Result                                        | What it means                                                                                                                                                                     |
| --------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Valid**                                     | The `hash` matches the rest of the request and your Secret Key. If the API still rejects it, check that the Public Key belongs to the same application and that `time` is recent. |
| **Invalid (hash mismatch), expected … got …** | The `hash` does not match. Common causes: the wrong Secret Key, or a parameter or field that changed after signing, including the order of the fields.                            |
| **Invalid, missing arguments: …**             | The request is missing `time`, `publicKey` or `hash`.                                                                                                                             |

You can also use **Validate a post request** to check a [webhook](https://docs.getbizprint.com/start-here/glossary/#webhook) body that BizPrint sent you, because webhooks are signed the same way. See [Receive print job updates from BizPrint with webhooks](https://docs.getbizprint.com/developers/webhooks/).

## Related pages

- [Sign BizPrint Print API requests](https://docs.getbizprint.com/developers/authentication/)
- [BizPrint Print API error codes and how to fix them](https://docs.getbizprint.com/developers/errors/)
- [Create a print job with the BizPrint Print API](https://docs.getbizprint.com/developers/create-print-job/)
- [Receive print job updates from BizPrint with webhooks](https://docs.getbizprint.com/developers/webhooks/)

Need help? Contact BizPrint support at <https://getbizprint.com/support/>.