This guide will get you up and running with the maesn API. To get started, you need to:

  • Register as a tenant and get an API key
  • Authenticate an end user to a target system
  • Make your first API call

After completing these steps, you are ready to start making calls to our Unified API. If you get stuck or have trouble, email us at

If you are impatient and would like to test maesn’s unified API right away, without registering, head over to our guide to testing with Postman.

Step 1: Create an account

Please contact us at the following link to get started. We will get in touch with you to create an account and provide you with an API key.

Step 2: Authenticate an end user to the target system

Once you have your API key your users can authenticate to the target system.

curl --request GET \
  --url '' \
    -H 'x-api-key: YOUR_API_KEY'

Replace :TARGET_SYSTEM with the target system you want to authenticate to. For example, to authenticate to Xero, replace :TARGET_SYSTEM with xero.

This endpoint will give back a URL that you need to show to the user to authenticate to the target system.

At the end of the flow we redirect the user back into your system based on a redirect URL you provide when we contact you for account creation.

At this point you will receive an account token that you can use to make API calls on behalf of the user.

Step 3: The first API call

Great! You are now ready to make your first call to the maesn API.

Here’s an example curl to the Accounting API to get you started:

curl --request GET \
  --url '' \
    -H 'x-api-key: YOUR_API_KEY' 'x-account-key: USER_ACCOUNT_KEY'