WebMCP File Converter
WebConverter is now a WebMCP server: AI agents can convert your files through document.modelContext — and the conversion still runs entirely in your browser.
WebMCP (the Web Model Context Protocol) lets a website hand structured tools directly to AI agents. WebConverter registers its conversion tools so an agent can convert images for you — with no upload, no API key, and no server ever touching your files.
What is WebMCP?
WebMCP is a draft W3C standard from the Web Machine Learning Community Group. It adds document.modelContext to the browser so a page can register tools — each with a name, a description and a JSON Schema — that an AI agent can discover and call. Unlike a classic MCP server there is no separate process and no token: the tool is the page's own JavaScript, so your data never leaves the tab.
Why a File Converter MCP with no upload?
Most AI assistants can only convert a file by uploading it to a third-party API. WebConverter's WebMCP tools run the same WebAssembly pipeline the human interface uses, inside a Web Worker. The agent passes bytes in and gets bytes out — no upload, no rate limit, no cost, near-zero CO₂. It is the most private way for an agent to convert a file.
How an agent uses it
The agent first calls list_supported_formats to learn which formats are valid, then calls convert_image with the file and a target format. The tool returns the converted file as base64 plus a data: URL. Everything is deterministic and described by JSON Schema, so the agent never has to guess.
Privacy and safety by design
The exposed tools are strictly read-only: they take bytes and return bytes. They never write to disk, never make network requests, and never read other tabs. An agent calling these tools has exactly the capability a person clicking “convert” has — and nothing more.
Registered WebMCP tools
These tools are registered with document.modelContext on every WebConverter page and mirrored on a programmatic registry so they work even before native browser support ships.
convert_image
Convert an image (BMP, DDS, GIF, HDR, ICO, JPEG, KTX, PGM, PIC, PNG, PPM, PSD, TGA, WebP, plus HEIC/AVIF via browser decode) to PNG, JPEG, BMP, TGA, HDR, EXR, KTX2 or WebP. Returns base64 + a data: URL. Runs locally, no upload.
images_to_pdf
Combine one or more images into a single PDF, one image per page, in the browser.
images_to_searchable_pdf
Combine images into a PDF and run Tesseract OCR so the resulting PDF has selectable, searchable text on top of the original pixels.
merge_pdfs
Merge multiple PDFs into one (all pages, in order) locally — no upload.
reorder_pdf_pages
Reorder the pages of a PDF and write a new PDF with the given order.
delete_pdf_pages
Drop the listed pages from a PDF, writing a new PDF of the remaining pages in their original order.
extract_pdf_text
Pull text out of a PDF (pdf.js) — plain text by default, or simple Markdown with one heading per page.
convert_document
Convert documents between formats with Pandoc (WASM): DOCX, ODT, RTF, HTML, Markdown, LaTeX, RST, EPUB, MediaWiki, … ↔ Markdown, HTML, plain, LaTeX, RST, AsciiDoc, DOCX, ODT. Lazy ~56 MB download on first use.
convert_audio
Convert an audio file — or extract the audio track from a video — to MP3, OGG, WAV or FLAC. Anything the browser can decode is accepted.
convert_video
Transcode a video to MP4 (H.264 + AAC), WebM (VP9 + Opus) or animated GIF with ffmpeg-wasm. Lazy per-variant download.
trim_video
Cut a clip from startTime → endTime out of a video with ffmpeg-wasm, locally.
remove_image_background
Produce a transparent PNG or WebP version of an image using a tiny U²-Net-P ONNX model plus a deterministic WASM matting pass.
transcribe_audio
Transcribe audio — or the audio track of a video — to text with timestamps using a quantised Whisper model (whisper.cpp WASM). English by default.
list_supported_formats
Enumerate every input/output format and engine across all WebMCP tools so an agent can plan a valid conversion.
Live demo — convert through the WebMCP tool
This calls the exact same convert_image tool an AI agent would call. Pick an image, choose a format, and the conversion runs locally in your browser.
Tip: in Chrome you can enable the native API at chrome://flags/#enable-webmcp-testing. This demo also works without it via the built-in tool registry.
WebMCP File Converter — FAQ
What is the WebMCP File Converter?
It is WebConverter exposed as a WebMCP server. Using document.modelContext, AI agents can call convert_image and list_supported_formats to convert images entirely in the browser — no upload and no API key.
Does it upload my files to a server?
No. The convert_image tool runs the same WebAssembly conversion the UI uses, inside a Web Worker. Your file never leaves the browser tab.
Which browsers support document.modelContext?
It is available behind a flag in recent Chrome builds (chrome://flags/#enable-webmcp-testing) and requires a secure context. WebConverter also exposes a programmatic tool registry so the same tools work before native support ships.
Is the File Converter MCP free?
Yes. There is no backend, no API key and no rate limit — it is as free as opening the page.
What formats can the MCP convert?
Input: BMP, DDS, GIF, HDR, ICO, JPEG, KTX, PGM, PIC, PNG, PPM, PSD, TGA, WebP. Output: PNG, JPEG, BMP, TGA, HDR, EXR, KTX2, WebP.
Is it safe to let an agent call these tools?
Yes. The tools are read-only — bytes in, bytes out. They never write files, make network requests, or read other tabs.
Browse everything WebConverter can convert
Every converter on the site is agent-ready. Explore the full catalogue or read how the WebMCP integration was built.
All conversions