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Open WebUI

Track usage, control costs, and add guardrails to your Open WebUI deployment

What is Open WebUI?

Open WebUI is a self-hosted, ChatGPT-style web interface for chatting with large language models. It runs entirely on your own infrastructure and connects to any server or provider that implements the OpenAI-compatible API.

By routing Open WebUI through FastRouter, you get:

  • 100+ models from OpenAI, Anthropic, Google, xAI, Meta, Groq, Mistral, and more through one endpoint—your whole team picks from a shared catalog with one key

  • Observability for every request: cost, tokens, latency, and model selection tracked in real time

  • Reliability through automatic failover across providers, response caching, and intelligent routing

  • Governance with per-key budgets, rate limits, model restrictions, role-based access, and project isolation

This guide covers connecting Open WebUI to FastRouter by adding it as an OpenAI-compatible connection.

Prerequisites

Quick Start

Step 1: Get Your FastRouter API Key

  1. Sign up or log in at fastrouter.ai

  2. Navigate to your project's Keys page

  3. Click Create User Key

  4. Copy the key immediately. FastRouter does not display the key again after creation.

Step 2: Add FastRouter as a Connection

  1. Open Open WebUI in your browser.

  2. Go to ⚙️ Admin Settings → Connections → OpenAI.

  1. Click ➕ Add Connection.

  1. Fill in:

    • URL: https://api.fastrouter.ai/api/v1

    • API Key: your FastRouter API key

  2. Click Save.

Step 3: Add the Models You Want

FastRouter exposes a large catalog, so rather than loading every model, add the specific slugs your team needs to the Model IDs (Filter) allowlist:

  1. In the connection settings, find Model IDs (Filter).

  2. Type a FastRouter model slug—for example openai/gpt-5.2—and click the + icon.

  3. Repeat for any other models (e.g., anthropic/claude-4.5-sonnet, x-ai/grok-code-fast-1).

  4. Click Save.

Note: Open WebUI verifies a connection by calling the provider's /models endpoint. Even if verification is slow or returns a warning, chat completions still work—the Model IDs (Filter) allowlist guarantees the models you listed appear in the selector.

Step 4: Start Chatting

Select a FastRouter model from the model dropdown in a new chat and send a message. The request routes through FastRouter, and every request, token count, and cost appears in your FastRouter Dashboard.

Use Open WebUI with 100+ Models

FastRouter uses the provider/model-name format. Add any catalog slug to the connection's Model IDs (Filter) and it becomes selectable in the chat model dropdown:

Explore the full model catalog

Automatic Model Selection

Let FastRouter pick the best model for each request based on query complexity, domain, and cost. Add this slug to your Model IDs (Filter) and select it like any other model:

Explore automatic model selection

FAQs

Configuration & Setup

Connection verification shows an error, but is the connection broken?

Not necessarily. Verification calls the /models endpoint; if it is slow or returns a non-200, you'll see a warning, but chat completions still work. Make sure your models are listed in the Model IDs (Filter) allowlist, and they will appear in the selector regardless.

Do I need a trailing slash on the URL?

No. Use exactly https://api.fastrouter.ai/api/v1 with no trailing slash.

Can I run multiple connections at once?

Yes. Each connection has a toggle to enable or disable it without deleting it, so you can keep FastRouter alongside other providers and switch as needed.

Can I restrict a key to only use specific models?

Yes. When creating or editing a key, use the Select Models setting to limit which models the key can access. FastRouter rejects requests to unauthorized models.

Costs & Budgeting

How do I control spend across a team using one shared instance?

Set a budget and rate limit on the FastRouter key, and use Dynamic Tags to attribute spend. The Dashboard breaks down costs by project, key, model, and tag.

Privacy & Security

Is my chat content sent to FastRouter's servers?

FastRouter acts as a pass-through gateway. Requests are routed to the model provider and responses are returned to your instance. Content logging can be disabled per key for sensitive workloads. See the Disable Content Logging option in key settings. For multi-user deployments, prefer a least-privilege key rather than an admin/master key.

Next Steps

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