# 83blue transfer

> Free, no-signup file transfer for AI agents. Upload a file with one HTTP request, an MCP tool call or an A2A message; you get back a capability url (one GET fetches it, DELETE removes it), a handoff url (paste into any chat: any model can fetch it for a full briefing), and a share url + password. Files up to 1 TB, auto-deleted after 1-180 days (default 180 for HTTP uploads, 30 for MCP tool calls). No accounts, no API keys, no cookies. Automated and bot use is welcome.

Key facts:

- Send (one request, up to 512 MB): `curl -F "file=@report.zip" https://upload.83blue.com/api/upload` returns JSON with `capability_url`, `handoff_url`, `url`, `password` and `sha256`. Optional fields: `password` (8-64 chars), `expires_days` (1-180).
- Receive: `curl -fL -OJ "https://upload.83blue.com/f/TOKEN/KEY"` (capability url), or `curl -fL -OJ "https://upload.83blue.com/api/download?token=TOKEN&password=PASSWORD"`.
- Delete when done: `curl -X DELETE "https://upload.83blue.com/f/TOKEN/KEY"`.
- Handoff url `https://upload.83blue.com/h/TOKEN/KEY`: fetching it returns a markdown briefing + manifest + download commands; `Accept: application/json` gives the same as data. Paste this one url into any chat with any model.
- Conversation handoff convention: put `HANDOFF.md` at the root of a zip bundle; the handoff url and receiving tools surface it first.
- Metadata only: `GET https://upload.83blue.com/api/info?token=&password=` (includes sha256 for files up to 1 GB).
- Files over 512 MB (up to 1 TB): resumable chunked protocol via `/api/create`, `/api/chunk`, `/api/status`.
- MCP server (Streamable HTTP, no authentication): `https://upload.83blue.com/mcp` with tools `share_text`, `share_file`, `share_conversation` (transcript + files behind one handoff url) and `receive_file`. Claude Code: `claude mcp add --transport http transfer https://upload.83blue.com/mcp`
- A2A: agent card at `https://upload.83blue.com/.well-known/agent-card.json`, JSON-RPC endpoint at `https://upload.83blue.com/a2a` (protocol 0.3.0, message/send, non-streaming). Works as the hosting layer for any A2A FileWithUri part.
- Rate limits: 3 simultaneous uploads site-wide (HTTP 429 + Retry-After when full: retry after a few seconds); downloads 1 Mbit/s per connection, 3 connections per IP.
- Self-test in four commands: upload a small file, GET its capability url, compare sha256, DELETE it.
- Fetching the homepage with a curl/wget user agent returns plain-text usage instructions.

## Docs

- [API reference](https://upload.83blue.com/docs): every endpoint with copy-paste curl examples, MCP setup for Claude Code, claude.ai, Cursor, VS Code and ChatGPT, A2A details, and the agent handoff pattern
- [Full reference for LLMs](https://upload.83blue.com/llms-full.txt): the complete API in one markdown file
- [OpenAPI 3.1 specification](https://upload.83blue.com/openapi.json)