SimpleX Chat

SimpleX Chat ↗ is a private, decentralised messaging platform where users own their contacts and groups. Unlike other platforms, SimpleX assigns no persistent user IDs — every contact is identified by an opaque internal ID generated at connection time, which makes it one of the most private messengers available.

Run hermes gateway setup and pick SimpleX for a guided walk-through.

• The simplex-chat CLI installed and running as a daemon
• Python package websockets (pip install websockets)

Download the latest release from the simplex-chat GitHub releases ↗ page:

# Linux / macOS binary
curl -L https://github.com/simplex-chat/simplex-chat/releases/latest/download/simplex-chat-ubuntu-22_04-x86_64 -o simplex-chat
chmod +x simplex-chat

The SimpleX Chat project does not publish a prebuilt Docker image for the chat client; to run it under Docker, build from source from the simplex-chat repository ↗.

simplex-chat -p 5225

The daemon listens on WebSocket at ws://127.0.0.1:5225 by default.

Via setup wizard

hermes gateway setup

Select SimpleX Chat and follow the prompts.

Via environment variables

Add these to ~/.hermes/.env:

SIMPLEX_WS_URL=ws://127.0.0.1:5225
SIMPLEX_ALLOWED_USERS=<contact-id-1>,<contact-id-2>
SIMPLEX_HOME_CHANNEL=<contact-id>

After starting the daemon, open a conversation with your agent contact. The numeric contactId appears in session logs. If you'd rather use the display name shown in the SimpleX UI, that works too — SIMPLEX_ALLOWED_USERS accepts either form.

By default all contacts are denied. You must either:

1. Set SIMPLEX_ALLOWED_USERS to a comma-separated list of contactIds and/or display names (e.g. SIMPLEX_ALLOWED_USERS=4,alice matches either contactId 4 or the contact whose display name is "alice"), or
2. Use DM pairing — send any message to the bot and it will reply with a pairing code. Enter that code via hermes pairing approve simplex <CODE>.

By default the adapter ignores group messages — a bot in a group otherwise processes every member's traffic. Opt-in explicitly:

SIMPLEX_GROUP_ALLOWED=12,34          # specific group IDs
# or
SIMPLEX_GROUP_ALLOWED=*              # any group the bot is in

Address groups by prefixing the chat ID with group:, e.g. simplex:group:12 as a cron deliver= target or in a hermes send call.

SimpleX works as a standalone send target — the daemon must be running, but a live gateway is not required for plain text:

hermes send --to simplex:alice "hello"          # DM by contact display name
hermes send --to simplex:group:12 "hello"       # group by numeric ID
hermes send --to simplex "hello"                # SIMPLEX_HOME_CHANNEL

While the gateway is running, the adapter enumerates your contacts and allowed groups into the channel directory (refreshed every 5 minutes), so hermes send --list shows them by name. Before the first gateway run the platform still appears in --list with a "no channels discovered yet" hint — direct targets like the ones above work regardless.

The adapter supports native SimpleX attachments in both directions:

• Inbound — incoming images, voice notes, and files are accepted via the daemon's XFTP flow (rcvFileDescrReady → /freceive → wait for rcvFileComplete) and surfaced as MessageEvent.media_urls with the appropriate MessageType (PHOTO, VOICE, TEXT + document).
• Outbound — send_image_file, send_voice, send_document, and send_video all use the structured /_send form with filePath, so the receiving SimpleX client renders images inline and plays voice notes inline rather than offering them as downloads.

Agent replies can also embed MEDIA:/path/to/file tags in plain text — the adapter strips the tag from the body and sends the file as either a voice note (audio extensions) or a document.

cronjob(
    action="create",
    schedule="every 1h",
    deliver="simplex",          # uses SIMPLEX_HOME_CHANNEL
    prompt="Check for alerts and summarise."
)

Or target a specific contact via the cron job's deliver: field, or from a shell script with the hermes send CLI:

hermes send simplex:<contact-id> "Done!"

• SimpleX never reveals phone numbers or email addresses — contacts use opaque IDs
• The connection between Hermes and the daemon is local WebSocket (ws://127.0.0.1:5225) — no data leaves your machine
• Messages are end-to-end encrypted by the SimpleX protocol before reaching the daemon

"Cannot reach daemon" — Ensure simplex-chat -p 5225 is running and the port matches SIMPLEX_WS_URL.

"websockets not installed" — Run pip install websockets.

Messages not received — Check that the contact's ID is in SIMPLEX_ALLOWED_USERS or approve them via DM pairing.