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Open WebUI

Open WebUI is a strong fit for self-hosted AI teams that want a private chat interface, local or EU-hosted models, and controlled access to external tools. Add Iteration Layer when users need production-grade document extraction, document-to-markdown conversion, image operations, generated PDFs, or spreadsheets from inside a chat workflow.

Use Iteration Layer as an OpenAPI tool server in Open WebUI.

This path uses normal API keys, works with Open WebUI’s tool-calling model, and avoids relying on MCP OAuth support in a self-hosted chat deployment.

Requirements

  • Open WebUI with tool calling enabled
  • A model configured for native function calling
  • An Iteration Layer API key from platform.iterationlayer.com
  • Access to the OpenAPI spec at https://api.iterationlayer.com/openapi.json

Add The OpenAPI Server

In Open WebUI, add a new OpenAPI server under the tool connections settings:

https://api.iterationlayer.com/openapi.json

Configure authentication as a bearer token using your Iteration Layer API key:

Authorization: Bearer YOUR_API_KEY

After the server is saved, Open WebUI can expose the Iteration Layer endpoints as callable tools for models that support native function calling.

Enable Native Tool Calling

Open WebUI recommends native function calling for modern models. In the model settings, set function calling to Native so the model receives Iteration Layer operations as structured tool definitions instead of prompt-only instructions.

Useful Workflows

Parse Documents In Chat

Ask the model to call document extraction with a schema:

Extract vendor, invoice number, issue date, due date, and total amount from this invoice. Return the fields as JSON and include confidence scores.

Prepare RAG Inputs

Use Document to Markdown before adding files to a knowledge workflow:

Convert this PDF to clean Markdown, preserve headings and tables, and summarize any sections with low OCR confidence.

Generate Deliverables

Use generation tools when the chat should produce files, not just text:

Create a one-page PDF approval memo from the extracted contract terms and include a table of risks.

MCP Option

Iteration Layer also exposes a remote MCP server at:

https://api.iterationlayer.com/mcp

Use MCP only if your Open WebUI deployment supports OAuth-enabled remote MCP servers. Iteration Layer MCP uses OAuth 2.1, not static API-key headers. If your Open WebUI version expects static headers for remote MCP, use the OpenAPI setup above.

Production Guidance

  • Keep Iteration Layer API keys in the Open WebUI server configuration, not in user prompts.
  • Prefer async webhooks for long-running jobs.
  • Use EU Hosting and Data Handling & Retention when documenting the deployment for security reviewers.
  • Restrict tool access to trusted users or groups if your Open WebUI instance is multi-user.