transmission-api

name	transmission-api
description	Transmission RPC reference covering JSON-RPC 2.0 transport, session token handling, torrent methods, session methods, and protocol versioning.

Skill: Transmission API

Purpose

Use this skill when you need to integrate with Transmission's RPC API.

Protocol

• Preferred transport: HTTP POST
• Default endpoint: http://host:9091/transmission/rpc
• Current spec: JSON-RPC 2.0
• Request parameters must be an object in params
• Response data is returned in result

Example request:

{
  "jsonrpc": "2.0",
  "params": {
    "fields": ["version"]
  },
  "method": "session_get",
  "id": 1
}

Authentication and session token

CSRF token

Most servers require X-Transmission-Session-Id.

• First request often gets 409 Conflict
• The response includes the correct X-Transmission-Session-Id
• Retry the same request with that header value

Authentication

• Optional HTTP Basic Auth
• Credentials are sent in Authorization: Basic ...

Method naming

• Transmission 4.1.0+ (rpc_version_semver 6.0.0+) uses JSON-RPC 2.0 and snake_case
• Older bespoke protocol and older kebab-case / camelCase strings are deprecated but still seen in existing clients

Torrent methods

Action methods

• torrent_start
• torrent_start_now
• torrent_stop
• torrent_verify
• torrent_reannounce

Common parameter:

• ids: integer id, array of ids/hashes, or "recently_active"

torrent_get

Request:

• optional ids
• required fields
• optional format: objects or table

Important field families:

• core status: id, hash_string, name, status, percent_done, eta, eta_idle
• storage: download_dir, files, file_stats, wanted, priorities, piece_count, piece_size, pieces
• transfer: rate_download, rate_upload, uploaded_ever, downloaded_ever, upload_ratio
• peers/trackers: peers, peers_from, trackers, tracker_stats, webseeds_ex
• queue and policy: queue_position, seed_ratio_limit, seed_idle_limit, labels, group, sequential_download

Status values:

Value	Meaning
0	stopped
1	queued to verify
2	verifying
3	queued to download
4	downloading
5	queued to seed
6	seeding

torrent_set

Common mutators:

• download_limit, download_limited
• upload_limit, upload_limited
• peer_limit
• files_wanted, files_unwanted
• priority_high, priority_normal, priority_low
• location
• queue_position
• labels
• group
• seed_ratio_limit, seed_ratio_mode
• seed_idle_limit, seed_idle_mode
• sequential_download
• sequential_download_from_piece
• tracker_list

torrent_add

Supply either:

• filename for URL or .torrent path
• metainfo for base64-encoded .torrent bytes

Useful optional parameters:

• download_dir
• paused
• labels
• peer_limit
• files_wanted, files_unwanted
• priority_*
• sequential_download
• sequential_download_from_piece

Success returns torrent_added; duplicate adds return torrent_duplicate.

Other torrent methods

• torrent_remove
  • params: ids, delete_local_data
• torrent_set_location
  • params: ids, location, move
• torrent_rename_path
  • params: ids (single torrent), path, name

Session methods

session_get / session_set

Important keys:

• networking: peer_port, port_forwarding_enabled, preferred_transports, encryption
• directories: download_dir, incomplete_dir, incomplete_dir_enabled
• queues: download_queue_enabled, download_queue_size, seed_queue_enabled, seed_queue_size
• speed limits: speed_limit_down, speed_limit_down_enabled, speed_limit_up, speed_limit_up_enabled
• alternate speeds: alt_speed_*
• seeding policy: seed_ratio_limit, seed_ratio_limited, idle_seeding_limit, idle_seeding_limit_enabled
• versioning: rpc_version_semver, version

Other session methods

• session_stats
• blocklist_update
• port_test
• session_close
• free_space
• queue movement: queue_move_top, queue_move_up, queue_move_down, queue_move_bottom
• bandwidth groups: group_set, group_get

Error object

JSON-RPC errors may include:

• code
• message
• data.error_string
• data.result

Versioning

• Prefer rpc_version_semver for compatibility checks
• rpc_version and rpc_version_minimum are deprecated
• X-Transmission-Rpc-Version may be returned on HTTP 409 responses on newer servers

Electorrent usage

Electorrent currently talks to Transmission using the legacy method names:

• session-get
• torrent-get
• torrent-add
• torrent action methods such as start/stop/remove

That works on current Transmission releases, but new integrations should prefer the JSON-RPC 2.0 snake_case forms from this spec.

Reference

• https://raw.githubusercontent.com/transmission/transmission/refs/heads/main/docs/rpc-spec.md