MCP server

The WebP MCP server for image optimization

Fast WebP Converter runs a remote MCP server at https://www.fastwebpconverter.com/api/mcp. Any assistant or coding agent that speaks MCP can convert an image or a batch to WebP, audit the images of a live page and read the account's allowance, without installing anything: Streamable HTTP, OAuth 2.1 with dynamic client registration, or an API key as a Bearer token.

Set it up in your clientCreate a free account
Streamable HTTPOAuth 2.1 or API keyFree account: 50 conversions a month
How it works

From a config line to a WebP file

The model decides what to convert; the server does the fetching, encoding and storing.

Step 1

Add the server

Paste https://www.fastwebpconverter.com/api/mcp into Claude, ChatGPT, Claude Code, Cursor, VS Code, Windsurf, Codex or any client with the Streamable HTTP transport.

Step 2

Sign in once

The client registers itself (dynamic client registration, scope fastwebp) and opens the Fast WebP Converter sign-in: an e-mail code or Google. Clients without OAuth send an API key as Authorization: Bearer instead.

Step 3

Call the tools

convert_image or convert_images return download links with the sizes; audit_page lists a page's images and the savings; get_account says what is left.

Set it up in your client

Claude (claude.ai, Desktop, phone): Customize, Connectors, Add custom connector with https://www.fastwebpconverter.com/api/mcp; this link(opens in new tab) opens the dialog already filled in. Step by step. ChatGPT: developer mode, Create, the same address with OAuth. Step by step.

Coding agents and editors:

Claude Code — bash
claude mcp add --transport http fastwebp https://www.fastwebpconverter.com/api/mcp
# then, in a Claude Code session: /mcp → fastwebp → Authenticate
~/.codex/config.toml — toml
[mcp_servers.fastwebp]
url = "https://www.fastwebpconverter.com/api/mcp"
# OAuth: run `codex mcp login fastwebp` once.
# Or use an API key from https://www.fastwebpconverter.com/account instead:
# bearer_token_env_var = "FASTWEBP_API_KEY"
~/.cursor/mcp.json (or .cursor/mcp.json in a project) — json
{
  "mcpServers": {
    "fastwebp": { "url": "https://www.fastwebpconverter.com/api/mcp" }
  }
}
.vscode/mcp.json — json
{
  "servers": {
    "fastwebp": { "type": "http", "url": "https://www.fastwebpconverter.com/api/mcp" }
  }
}
~/.codeium/windsurf/mcp_config.json — json
{
  "mcpServers": {
    "fastwebp": {
      "serverUrl": "https://www.fastwebpconverter.com/api/mcp",
      "headers": { "Authorization": "Bearer YOUR_FASTWEBP_API_KEY" }
    }
  }
}
Any other client — json
{
  "mcpServers": {
    "fastwebp": { "type": "http", "url": "https://www.fastwebpconverter.com/api/mcp" }
  }
}

https://www.fastwebpconverter.com/mcp is a short alias of the same server. The Claude Code plugin (/plugin marketplace add gabrielstik/fastwebp-plugin) adds the server plus two skills and a /webp command.

OAuth or an API key

OAuth 2.1 (recommended). The client discovers Fast WebP Converter's authorization server from the first unauthenticated call, registers itself (dynamic client registration), opens the sign-in page and receives a token for the fastwebp scope. Nothing to paste. Sign-in is an e-mail code or Google, and a free account is created on the way if needed.

API key. For clients without OAuth, CI jobs and headless agents: create a key on your account page and send it as Authorization: Bearer fwk_.... The same key works for the REST API. Keep it in an environment variable or a secret store, never in a repository.

Cursor, with an API key — json
{
  "mcpServers": {
    "fastwebp": {
      "url": "https://www.fastwebpconverter.com/api/mcp",
      "headers": { "Authorization": "Bearer ${env:FASTWEBP_API_KEY}" }
    }
  }
}
VS Code, with an API key (asked once, stored by VS Code) — json
{
  "inputs": [
    { "type": "promptString", "id": "fastwebp-key", "description": "Fast WebP Converter API key", "password": true }
  ],
  "servers": {
    "fastwebp": {
      "type": "http",
      "url": "https://www.fastwebpconverter.com/api/mcp",
      "headers": { "Authorization": "Bearer ${input:fastwebp-key}" }
    }
  }
}
Claude Code, with an API key instead of OAuth — bash
claude mcp add --transport http fastwebp https://www.fastwebpconverter.com/api/mcp \
  --header "Authorization: Bearer $FASTWEBP_API_KEY"

The tools

Results come back as text with the sizes and links, so any client can use them; Claude and ChatGPT also render them as an interactive card in the conversation.

Tools served at the MCP address

ToolWhat it doesEffect
convert_imageConverts one image to WebP, from a public URL or from image data (base64), with quality, maximum width and lossless options. Returns a download link, the original and WebP sizes, the dimensions and the percentage saved.1 conversion; stores the WebP behind a download link
convert_imagesConverts several images in one call (up to 5 on Free, 50 on Pro) and returns one ZIP download link with the sizes of each file.1 conversion per image; stores one ZIP
audit_pageReads a public web page, lists its images with their format and weight, and estimates how much converting them to WebP would save. A starting point for a page-speed plan. The same audit is free on the website at https://www.fastwebpconverter.com/audit.Read-only; uses no conversion
get_accountYour plan, the conversions used and left this month and when the allowance resets.Read-only, free
get_pricingThe current plans and prices, so the assistant quotes the real figures instead of guessing.Read-only, free

Formats: JPG, PNG, GIF, WebP, AVIF, TIFF and SVG. Animated GIFs come out as animated WebP. HEIC photos and BMP files are not read on the server: the browser converter handles them (HEIC in Safari).

audit_page uses no conversion, and the same audit is free on the website: paste a URL in the image audit and see each image's real WebP saving, no account needed.

Local files and coding agents

A remote server cannot read your disk. Images that are already online go by URL. For files in a repository, an agent can send small images as base64 to convert_image, but the efficient route is the REST API, which takes the file as an upload and writes the WebP straight to disk:

What the agent runs for a local file — bash
curl -sS -H "Authorization: Bearer $FASTWEBP_API_KEY" \
  -F file=@public/hero.png -F quality=80 -F max_width=1600 \
  https://www.fastwebpconverter.com/api/v1/convert -o public/hero.webp

The Claude Code plugin's optimize-images-to-webp skill does exactly that: inventory, conversion, references updated with <picture> fallbacks, and a report of the bytes saved. Uploads are limited to 4 MB; larger images go by URL.

Limits and plans

A free Fast WebP Converter account is the way to try it: 50 conversions a month on the server, shared by Claude, ChatGPT, every MCP client and the API. Pro is full access, paid monthly, yearly or once for life ($4.99/month, $29/year or $59 once), with 10,000 server conversions a month (fair use). The monthly allowance resets on the 1st (UTC).

Per account; the MCP server and the API share the same allowance

PlanPriceServer conversionsImages per batch callImage by URL up toAPI requests a minuteDownload links kept
FreeFree50 a month510 MB1024 hours
Pro$4.99/month, $29/year or $59 once10,000 a month5025 MB1203 days

When the allowance is used up, conversion tools answer with a clear message and the account link instead of failing silently. get_account and get_pricing keep working.

Questions

Yes. Fast WebP Converter works inside Claude, ChatGPT and any MCP client: ask the assistant to convert an image, a batch or the images of a whole web page to WebP, and it calls Fast WebP Converter's server, which encodes them with libwebp and hands back download links with the size before and after. The address is https://www.fastwebpconverter.com/api/mcp (Streamable HTTP, OAuth 2.1 or an API key).

No. It uses OAuth 2.1 with dynamic client registration: the client registers itself and you sign in with an e-mail code or Google. For clients without OAuth, an API key from https://www.fastwebpconverter.com/account works as a Bearer token.

Any client with the Streamable HTTP transport: Claude (web, Desktop, phone, Claude Code), ChatGPT in developer mode, Codex, Cursor, VS Code, Windsurf and others. The interactive result card shows in hosts that render MCP apps, such as Claude and ChatGPT; elsewhere the tools return text and links.

Not by reading your disk: it is a remote server. Images online go by URL; an agent can send small images as base64, or call the REST API with an upload (up to 4 MB), which the Claude Code plugin does for you.

Each converted image counts as one conversion of the account's monthly allowance; audit_page, get_account and get_pricing use none. A free Fast WebP Converter account is the way to try it: 50 conversions a month on the server, shared by Claude, ChatGPT, every MCP client and the API. Pro is full access, paid monthly, yearly or once for life ($4.99/month, $29/year or $59 once), with 10,000 server conversions a month (fair use). The monthly allowance resets on the 1st (UTC).

No. Fast WebP Converter converts the images a tool sends and keeps the WebP result only as long as its download link lasts. What the assistant itself does with the conversation is governed by your assistant's own settings.

Related

WebP in Claude

Connector, Claude Code command and the plugin.

Read more

WebP in ChatGPT

The app in developer mode, and a Custom GPT.

Read more

WebP conversion API

The REST API: uploads, URLs, JSON mode, errors.

Read more

WebP and Core Web Vitals

Why lighter images move LCP, and what to convert first.

Read more

Give your agent a WebP encoder

Create the free account it signs in with (50 conversions a month) and paste https://www.fastwebpconverter.com/api/mcp into your client.

Set it upCreate a free account