Gusto TypeScript Library

The Gusto TypeScript library provides convenient access to the Gusto API from JavaScript/TypeScript.

Reference

A full reference of the SDK is available here.

Installation

npm install --save @fern-api/gusto
# or
yarn add @fern-api/gusto

Usage

import { GustoClient, Gusto } from 'gusto';

const gusto = new GustoClient({
  auth: {
    type: "token", 
    token: "..." // YOUR_ACCESS_TOKEN
  }
});

await gusto.employee.update("employee_id", {
    version: "db0edd04aaac4506f7edab03ac855d56",
    firstName: "Soren",
    middleInitial: "A",
    lastName: "Kierkegaard",
    dateOfBirth: "1995-05-05",
    email: "[email protected]",
    ssn: "123456294",
    twoPercentShareholder: false,
});

Authentication

System Access Token

The SDK supports authentication using System Access Tokens and automatically refreshing before expiry. See the System Access Token documentation for more details on how to obtain and use System Access Tokens.

const gusto = new GustoClient({
  auth: {
    type: "system_access_token",
    clientId: "YOUR_CLIENT_ID",
    clientSecret: "YOUR_CLIENT_SECRET"
  }
});

Company Access Token

The SDK supports authentication using Company Access Tokens and automatically handles token refresh. See the Company Access Token documentation for more details on how to obtain and use Company Access Tokens. Company Access Tokens allow you to make API calls on behalf of a specific company after completing the OAuth flow.

const gusto = new GustoClient({
  auth: {
    type: "company_access_token",
    clientId: "YOUR_CLIENT_ID", 
    clientSecret: "YOUR_CLIENT_SECRET",
    accessToken: "YOUR_ACCESS_TOKEN",
    refreshToken: "YOUR_REFRESH_TOKEN",
    redirectUri: "YOUR_REDIRECT_URI"
  }
});

Raw Token

If you're managing token acquisition and refresh logic yourself, you can pass in any token directly using the token auth type. This can be used with System Access Tokens or Company Access Tokens, and won't do any sort of refreshing.

const gusto = new GustoClient({
  auth: {
    type: "token",
    token: "YOUR_TOKEN"
  }
});

Request and Response Types

The SDK exports all request and response types as TypeScript interfaces. Simply import them under the Gusto namespace:

import { Gusto } from "gostu"; 

const user: Gusto.PaidTimeOff = {
  name: "Vacation Hours"
  policyName: "...",
}

Exception Handling

When the API returns a non-success status code (4xx or 5xx response), a subclass of GustoError will be thrown:

import { GustoError } from 'gusto';

try {
  await gusto.company.payroll.create(...);
} catch (err) {
  if (err instanceof GustoError) {
    console.log(err.statusCode); 
    console.log(err.message);
    console.log(err.body); 
  }
}

Retries

The TypeScript SDK is instrumented with automatic retries with exponential backoff. A request will be retried as long as the request is deemed retriable and the number of retry attempts has not grown larger than the configured retry limit (default: 2).

A request is deemed retriable when any of the following HTTP status codes is returned:

• 408 (Timeout)
• 429 (Too Many Requests)
• 5XX (Internal Server Errors)

Use the maxRetries request option to configure this behavior.

const response = await gusto.employee.update(..., {
  maxRetries: 0 // override maxRetries at the request level
});

Timeouts

The SDK defaults to a 60 second timout. Use the timeoutInSeconds option to configure this behavior.

const response = await gusto.employee.update(..., {
  timeoutInSeconds: 30 // override timeout to 30s
});

Runtime compatiblity

The SDK defaults to node-fetch but will use the global fetch client if present. The SDK works in the following runtimes:

The following runtimes are supported:

• Node.js 15+
• Vercel
• Cloudflare Workers
• Deno v1.25+
• Bun 1.0+
• React Native

Customizing Fetch client

The SDK provides a way for you to customize the underlying HTTP client / Fetch function. If you're running in an unsupported environment, this provides a way for you to break the glass and ensure the SDK works.

import { GustoClient } from 'gusto';

const gusto = new GustoClient({
  token: "...",
  fetcher: // provide your implementation here
});

Beta status

This SDK is in beta, and there may be breaking changes between versions without a major version update. Therefore, we recommend pinning the package version to a specific version in your package.json file. This way, you can install the same version each time without breaking changes unless you are intentionally looking for the latest version.

Contributing

While we value open-source contributions to this SDK, this library is generated programmatically. Additions made directly to this library would have to be moved over to our generation code, otherwise they would be overwritten upon the next generated release. Feel free to open a PR as a proof of concept, but know that we will not be able to merge it as-is.

We suggest opening an issue first to discuss with us!