hermes-agent/website/docs/user-guide/messaging/simplex.md

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.

Prerequisites

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

Install simplex-chat

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.

Start the daemon

simplex-chat -p 5225

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

Configure Hermes

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>

Variable	Required	Description
SIMPLEX_WS_URL	Yes	WebSocket URL of the simplex-chat daemon
SIMPLEX_ALLOWED_USERS	Recommended	Comma-separated allowlist. Each entry can be a numeric contactId or a display name — both forms work.
SIMPLEX_ALLOW_ALL_USERS	Optional	Set true to allow every contact (use carefully)
SIMPLEX_AUTO_ACCEPT	Optional	Auto-accept incoming contact requests (default: true)
SIMPLEX_GROUP_ALLOWED	Optional	Comma-separated group IDs the bot participates in, or * for any group. Omit to ignore group messages entirely
SIMPLEX_HOME_CHANNEL	Optional	Default contact/group ID for cron job delivery
SIMPLEX_HOME_CHANNEL_NAME	Optional	Human label for the home channel
HERMES_SIMPLEX_TEXT_BATCH_DELAY	Optional	Quiet-period seconds (default: 0.8) used to concatenate rapid-fire inbound text messages into one event

Find your contact ID or display name

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

Authorization

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>.

Group chats

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 in send_message or as a cron deliver= target.

Attachments

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.

Using SimpleX with cron jobs

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

Or target a specific contact:

send_message(target="simplex:<contact-id>", message="Done!")

Privacy notes

• 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

Troubleshooting

"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.