---
title: "Send Messages"
method: POST
path: "/api/notifications/"
tags: ["notifications"]
---

# Send Messages

`POST /api/notifications/`

Send E2E encrypted messages to one or more users.

Each message is encrypted with the recipient's individual shared key.
Creates bilateral notifications visible to both sender and recipient.
If recipient is online via WebSocket, delivers in real-time.

Returns the created notifications.

## Request body

- SendMessageRequest — Send E2E encrypted messages to one or more users. Each recipient gets the same logical message, encrypted with their individual shared key (derived from X25519 DH).
  - `messages` MessageRecipient[], required
    - `recipient_ext_id` string, required
    - `content` string, required

## Response `201`

Successful Response

- NotificationResponse[]
  - `type` string, required
  - `external_id` string, required
  - `sender` UserResponse, required — Standard user representation used across all endpoints. Used for: login response, workspace users, contacts (when registered).
    - `external_id` string, required
    - `email` string, required
    - `given_name` string, required
    - `family_name` string, required
    - `picture` string, nullable
    - `encryption_public_key` string, required
  - `recipient` UserResponse, required — Standard user representation used across all endpoints. Used for: login response, workspace users, contacts (when registered).
    - `external_id` string, required
    - `email` string, required
    - `given_name` string, required
    - `family_name` string, required
    - `picture` string, nullable
    - `encryption_public_key` string, required
  - `workspace_ext_id` string, nullable
  - `content` string, nullable
  - `new` boolean
  - `created_at` string, date-time, required
  - `updated_at` string, date-time, required

## Other responses

- `422` — Validation Error

## Changes

- **2025-12-31** `d14bca97ba86` — 1 info
  - endpoint added

[Change history](https://skmtc.dev/arbicity/apis/arbi/changes/api/notifications/post.md)

---

[API](https://skmtc.dev/arbicity/apis/arbi.md) · [All operations](https://skmtc.dev/arbicity/apis/arbi/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/arbicity/arbi/revisions/b9aa4615da16/schema)