FileMaker Data API with Node.js

Beginner

Build a reusable Node.js client for the FileMaker Data API with session management, automatic token refresh, and typed responses.

What you'll learn

How to structure a reusable FileMaker API client class
How to manage session tokens with automatic refresh
How to type Data API responses with TypeScript generics
How to handle network errors vs. FM application errors

A raw fetch loop works for one-off scripts, but production Node.js integrations need session pooling, automatic re-authentication on 401 errors, and typed interfaces. A small FileMaker client class encapsulates these concerns so application code stays clean.

1/4

Client class skeleton

Encapsulate the base URL, credentials, and session token in a class. Provide a login method and a private request method that handles auth headers.

FileMaker Script

class FileMakerClient {
  private token: string | null = null;

  constructor(
    private readonly host: string,
    private readonly database: string,
    private readonly user: string,
    private readonly password: string
  ) {}

  async login(): Promise<void> {
    const resp = await fetch(
      `${this.host}/fmi/data/v1/databases/${this.database}/sessions`,
      {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          Authorization: 'Basic ' + btoa(`${this.user}:${this.password}`),
        },
        body: '{}',
      }
    );
    const json = await resp.json();
    this.token = json.response.token;
  }

  async logout(): Promise<void> {
    if (!this.token) return;
    await fetch(
      `${this.host}/fmi/data/v1/databases/${this.database}/sessions/${this.token}`,
      { method: 'DELETE' }
    );
    this.token = null;
  }
}