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Before you begin

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Download the developer integration kit

The Developer Integration Kit is the fastest way to get started. It includes:
  • Complete API documentation
  • Sample requests and responses
  • A Postman collection
  • An AI integration accelerator (located in the skills/ folder) that works with Cursor and other AI-assisted IDEs
Download the Developer Integration Kit and open it in your IDE. After providing your API key, the included copilot can guide you through:
  • Authentication
  • Request construction
  • Payload validation
  • Response interpretation
Using the provided samples and tools, you can stand up and test a working integration in minutes. As a reminder, you can integrate in three quick steps:
1

Retain the payroll context

Your application retains the STE payroll calculation log or JSON request (the payroll context).
2

Send the data to the STL API

You send that data to the STL API.
3

Display the explanation

The API returns a structured explanation and you display it in your UI.
The fastest way to see STL in action is with the provided Postman collection.
1

Import the Postman collection and environment file

Download the collection and environment (.zip), then extract it to get both files:
  • symmetry-tax-logic-api.postman_collection.json — sample requests to all endpoints, including /explain.
  • symmetry-tax-logic-api.postman_environment.json — variables used in requests. Enter your unique API key provided by Symmetry.
2

Configure your Postman environment

Configure your Postman environment using the following variables:Leave the other variables as-is — they are auto-populated by the collection scripts:
  • bearer_token — set automatically after authentication
  • conversation_id — set automatically after an explain call
  • api_version — defaults to v1
3

Run the Full Workflow

  • In the Tax Logic AI API workspace, click on the “3. Full Workflow (Run All)” folder
  • Click the Run button (▶) at the top of the folder — this opens the Collection Runner
  • Click “Run Tax Logic API” to start
The runner executes two steps in sequence:
  • Step 1: Authenticate — calls GET {{auth_url}}/authentication/login with your API key and stores the Bearer token
  • Step 2: Explain Tax — calls POST {{base_url}}/v1/explain with sample PayCalc data (FICA, Medicare, FIT)
4

Check the Test Results tab

Both steps should show green checkmarks.
5

Review the explanations

Click on Step 2 to see the AI-generated tax explanations in the response body.

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Option 2: Run a sample client

Pick your language and follow the README in the corresponding folder within the Developer Integration Kit.

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Option 3: Dive into the full tutorial

Read the Full Workflow for a step-by-step walkthrough from authentication through UI display.

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Explore with Swagger

Our Swagger documentation lets you explore and test the STL API endpoints interactively: Swagger.
1

Authorize access

To test STL API endpoints using our Swagger documentation, authenticate with your API key:
  • Click Authorize
  • Enter your API key in the value field and click Authorize
2

Test an endpoint

  • Navigate to any endpoint (for example, /explain)
  • Click Try it out
  • Click Execute
Swagger will display the API’s response, including the status code, response body, and headers.