---
id: kb-2026-00088
title: WebSocket API
schema_type: TechArticle
category: computer-science
language: en
confidence: medium
last_verified: "2026-05-28"
created_date: "2026-05-22"
generation_method: ai_structured
derived_from_human_seed: true
conflict_of_interest: none_declared
is_live_document: false
data_period: static
atomic_facts:
  - id: fact-computer-science-001
    statement: RFC 6455 defines the WebSocket Protocol for two-way communication between clients and remote hosts.
    source_title: The WebSocket Protocol
    source_url: https://www.rfc-editor.org/rfc/rfc6455
    confidence: medium
  - id: fact-computer-science-002
    statement: >-
      The browser WebSocket interface exposes methods and events for opening, sending, receiving, and closing a
      WebSocket connection.
    source_title: WebSocket
    source_url: https://developer.mozilla.org/en-US/docs/Web/API/WebSocket
    confidence: medium
  - id: fact-computer-science-003
    statement: The WebSocket readyState property reports whether a connection is connecting, open, closing, or closed.
    source_title: "WebSocket: readyState property"
    source_url: https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/readyState
    confidence: medium
completeness: 0.88
primary_sources:
  - title: The WebSocket Protocol
    type: rfc
    year: 2011
    institution: IETF
    url: https://www.rfc-editor.org/rfc/rfc6455
  - title: WebSocket
    type: documentation
    year: 2026
    institution: MDN Web Docs
    url: https://developer.mozilla.org/en-US/docs/Web/API/WebSocket
  - title: "WebSocket: readyState property"
    type: documentation
    year: 2026
    institution: MDN Web Docs
    url: https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/readyState
secondary_sources: []
updated: "2026-05-28"
known_gaps:
  - HTTP/2 and HTTP/3 transport interactions for WebSocket-like use cases
  - Backpressure and scaling concerns for high-volume real-time systems
disputed_statements: []
---
## TL;DR
The WebSocket API gives browsers a JavaScript interface for bidirectional communication with a server over the WebSocket protocol. It is useful for chat, collaboration, notifications, dashboards, and other real-time interfaces.

## Core Explanation
A client creates a WebSocket with a ws or wss URL, then listens for open, message, error, and close events. The readyState property exposes connection state, and send() transmits data when the connection is open.

## Detailed Analysis
WebSocket is not a general replacement for HTTP. It is a persistent connection model, so production systems need connection lifecycle handling, backpressure, authentication, authorization, and scaling design.

## Further Reading
- RFC 6455
- MDN WebSocket
- MDN readyState

## Related Articles

- [API Gateway](../api-gateway.md)
- [Broadcast Channel API](../broadcast-channel-api.md)
- [Canvas API](../canvas-api.md)