One Auth Integration Guide

One Auth is a drop-in authentication widget that lets your users connect their third-party apps to your application. It supports 250+ integrations — both OAuth and non-OAuth — including Gmail, Slack, HubSpot, Salesforce, QuickBooks, and more. Configuration is managed per-project via the One Dashboard, enabling multi-tenant architectures where each project maintains its own set of visible apps, OAuth credentials, and scopes.

What is One Auth?

One Auth is a pre-built, embeddable authentication component that:

• Lets your users connect their third-party apps (Gmail, Slack, HubSpot, etc.) to your application
• Supports both OAuth and non-OAuth integrations across 250+ platforms
• Handles token management and refresh automatically
• Works with any frontend framework (React, Vue, vanilla JS)
• Configurable per-project via the One Dashboard — choose which apps are visible, use your own OAuth credentials or One's defaults, and customize scopes
• Requires a backend token endpoint

Prerequisites

• One API key from https://app.withone.ai/settings/api-keys
• Backend capable of making authenticated API calls
• Frontend capable of running JavaScript