---
summary: "Zalo Bot API setup, long-polling or webhook mode, and Fased DM or group policy."
read_when:
  - Working on Zalo features or webhooks
title: "Zalo"
---

# Zalo (Bot API)

Zalo is the official bot path for teams or businesses that need to meet users
inside the Zalo ecosystem. The plugin can long-poll by default or switch to a
webhook model, while Fased keeps DM policy and group policy separate.

Status: experimental. DMs are supported, and groups are available behind explicit policy controls.

## Setup from Agent > Channels

Zalo ships with Fased as a local bundled channel extension. You do not need to
download an npm package in a normal install.

Open **Agents**, select the Agent, then use **Agent > Channels > Zalo**. Enter
the bot token, save the channel, then restart the gateway if the UI reports
that the runtime still needs to load.

## Quick setup (beginner)

If you are just starting, use long-polling first. Move to webhook mode only
when you need it and can expose a dedicated HTTPS path safely.

1. Set the token:
   - Env: `ZALO_BOT_TOKEN=...`
   - Or **Agent > Channels > Zalo**.
2. Restart the gateway if the UI asks for it.
3. DM access is pairing by default; approve the pairing code on first contact.

Minimal config:

```json5
{
  channels: {
    zalo: {
      enabled: true,
      botToken: "12345689:abc-xyz",
      dmPolicy: "pairing",
    },
  },
}
```

## What it is

Zalo is a Vietnam-focused messaging app. Its Bot API lets the Gateway run a bot
for 1:1 conversations. It is a good fit for support or notifications where you
want deterministic routing back to Zalo.

- A Zalo Bot API channel owned by the Gateway.
- Deterministic routing: replies go back to Zalo; the model never chooses channels.
- DMs share the agent's main session.
- Groups are supported with policy controls and default to fail-closed
  allowlist behavior.

## Setup (fast path)

### 1) Create a bot token (Zalo Bot Platform)

1. Go to [https://bot.zaloplatforms.com](https://bot.zaloplatforms.com) and sign in.
2. Create a new bot and configure its settings.
3. Copy the bot token (format: `12345689:abc-xyz`).

### 2) Configure the token (env or config)

Example:

```json5
{
  channels: {
    zalo: {
      enabled: true,
      botToken: "12345689:abc-xyz",
      dmPolicy: "pairing",
    },
  },
}
```

Env option: `ZALO_BOT_TOKEN=...` (works for the default account only).

Multi-account support uses `channels.zalo.accounts` with per-account tokens and
optional `name`.

3. Restart the gateway. Zalo starts when a token is resolved (env or config).
4. DM access defaults to pairing. Approve the code when the bot is first contacted.

## How it works (behavior)

- Inbound messages are normalized into the shared channel envelope with media placeholders.
- Replies always route back to the same Zalo chat.
- Long-polling by default; webhook mode available with `channels.zalo.webhookUrl`.

## Limits

- Outbound text is chunked to 2000 characters (Zalo API limit).
- Media downloads/uploads are capped by `channels.zalo.mediaMaxMb` (default 5).
- Streaming is blocked by default due to the 2000 char limit making streaming less useful.

## Access control (DMs)

### DM access

- Default: `channels.zalo.dmPolicy = "pairing"`. Unknown senders receive a
  pairing code. Messages wait for approval, and codes expire after 1 hour.
- Approve via:
  - `fased pairing list zalo`
  - `fased pairing approve zalo <CODE>`
- Pairing is the default token exchange. Details: [Pairing](/channels/pairing)
- `channels.zalo.allowFrom` accepts numeric user IDs (no username lookup available).

## Access control (Groups)

- `channels.zalo.groupPolicy` controls group inbound handling: `open | allowlist | disabled`.
- Default behavior is fail-closed: `allowlist`.
- `channels.zalo.groupAllowFrom` restricts which sender IDs can trigger the bot
  in groups.
- If `groupAllowFrom` is unset, Zalo falls back to `allowFrom` for sender checks.
- `groupPolicy: "disabled"` blocks all group messages.
- `groupPolicy: "open"` allows any group member (mention-gated).
- Runtime note: if `channels.zalo` is missing entirely, runtime still falls back to `groupPolicy="allowlist"` for safety.

## Long-polling vs webhook

- Default: long-polling (no public URL required).
- Webhook mode: set `channels.zalo.webhookUrl` and `channels.zalo.webhookSecret`.
  - The webhook secret must be 8-256 characters.
  - Webhook URL must use HTTPS.
  - Zalo sends events with `X-Bot-Api-Secret-Token` header for verification.
  - Gateway HTTP handles webhook requests at `channels.zalo.webhookPath`.
  - Requests must use `Content-Type: application/json` (or `+json` media types).
  - Duplicate events (`event_name + message_id`) are ignored for a short replay window.
  - Burst traffic is rate-limited per path/source and may return HTTP 429.

Note: getUpdates polling and webhook mode are mutually exclusive per Zalo API
docs.

## Supported message types

- **Text messages**: Full support with 2000 character chunking.
- **Image messages**: Download and process inbound images; send images via `sendPhoto`.
- **Stickers**: Logged but not fully processed (no agent response).
- **Unsupported types**: Logged (e.g., messages from protected users).

## Capabilities

| Feature         | Status                                                   |
| --------------- | -------------------------------------------------------- |
| Direct messages | ✅ Supported                                             |
| Groups          | ⚠️ Supported with policy controls (allowlist by default) |
| Media (images)  | ✅ Supported                                             |
| Reactions       | ❌ Not supported                                         |
| Threads         | ❌ Not supported                                         |
| Polls           | ❌ Not supported                                         |
| Native commands | ❌ Not supported                                         |
| Streaming       | ⚠️ Blocked (2000 char limit)                             |

## Delivery targets (CLI/cron)

- Use a chat id as the target.
- Example: `fased message send --channel zalo --target 123456789 --message "hi"`.

## Troubleshooting

**Bot doesn't respond:**

- Check that the token is valid: `fased channels status --probe`
- Verify the sender is approved (pairing or allowFrom)
- Check gateway logs: `fased logs --follow`

**Webhook not receiving events:**

- Ensure webhook URL uses HTTPS
- Verify secret token is 8-256 characters
- Confirm the gateway HTTP endpoint is reachable on the configured path
- Check that getUpdates polling is not running (they're mutually exclusive)

## Configuration reference (Zalo)

Full configuration: [Configuration](/gateway/configuration)

Provider options:

- `channels.zalo.enabled`: enable/disable channel startup.
- `channels.zalo.botToken`: bot token from Zalo Bot Platform.
- `channels.zalo.tokenFile`: read token from file path.
- `channels.zalo.dmPolicy`: `pairing | allowlist | open | disabled` (default: pairing).
- `channels.zalo.allowFrom`: DM allowlist (user IDs). `open` requires `"*"`. The wizard will ask for numeric IDs.
- `channels.zalo.groupPolicy`: `open | allowlist | disabled` (default: allowlist).
- `channels.zalo.groupAllowFrom`: group sender allowlist (user IDs). Falls back to `allowFrom` when unset.
- `channels.zalo.mediaMaxMb`: inbound/outbound media cap (MB, default 5).
- `channels.zalo.webhookUrl`: enable webhook mode (HTTPS required).
- `channels.zalo.webhookSecret`: webhook secret (8-256 chars).
- `channels.zalo.webhookPath`: webhook path on the gateway HTTP server.
- `channels.zalo.proxy`: proxy URL for API requests.

Multi-account options:

- `channels.zalo.accounts.<id>.botToken`: per-account token.
- `channels.zalo.accounts.<id>.tokenFile`: per-account token file.
- `channels.zalo.accounts.<id>.name`: display name.
- `channels.zalo.accounts.<id>.enabled`: enable/disable account.
- `channels.zalo.accounts.<id>.dmPolicy`: per-account DM policy.
- `channels.zalo.accounts.<id>.allowFrom`: per-account allowlist.
- `channels.zalo.accounts.<id>.groupPolicy`: per-account group policy.
- `channels.zalo.accounts.<id>.groupAllowFrom`: per-account group sender allowlist.
- `channels.zalo.accounts.<id>.webhookUrl`: per-account webhook URL.
- `channels.zalo.accounts.<id>.webhookSecret`: per-account webhook secret.
- `channels.zalo.accounts.<id>.webhookPath`: per-account webhook path.
- `channels.zalo.accounts.<id>.proxy`: per-account proxy URL.
