PostHog Project Structure

The all-in-one platform for product analytics, session replay, and feature flags. PostHog is built as a highly performant polyglot monorepo, combining a Django backend, a React frontend, and a specialized Rust-based ingestion engine.

Updated 2025-12-30

#posthog #analytics #django #react #rust #clickhouse #monorepo #open-source

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Project Directory

posthog/

The core Django application

api/

REST API endpoints

models/

Data models

hogql/

HogQL (SQL-like) engine

frontend/

Main dashboard (React)

src/

React source code

scenes/

Page-level components

plugin-server/

Node.js service for ingestion and plugins

rust/

High-performance services (e.g., Capture)

ee/

Enterprise edition features

infra-scripts/

Deployment and infra tools

package.json

Root workspace file

Repository Info

Repository-PostHog/posthog
Stars-20k+
License-MIT / Proprietary (ee)
Last Analyzed-December 2025

Tech Stack

Backend-Python (Django)
Frontend-React
Ingestion-Node.js & Rust
Database-ClickHouse & PostgreSQL
Queuing-Kafka & Redis

Architecture Notes

PostHog is a 'Product OS' that manages massive data volumes. Its architecture is built around ClickHouse for lightning-fast analytical queries and Kafka for high-throughput data ingestion. The monorepo strategy allows them to manage closely coupled services—like the Django API and the Node.js plugin server—while using Rust for performance-critical ingestion paths. They've also pioneered 'HogQL', an internal SQL dialect that enables powerful, type-safe data exploration directly from their frontend.

Key Directories

posthog/-Houses the primary business logic, API, and the HogQL analytical engine
frontend/-A complex React application featuring a data-rich dashboard and session replay tools
plugin-server/-Handles real-time data processing, plugin execution, and Kafka ingestion
rust/-Contains optimized services for capturing events at scale with minimal latency

Why This Structure?

PostHog is one of the most sophisticated open-source architectures available. It's a goldmine for anyone interested in high-volume data ingestion, analytical databases (ClickHouse), and building a platform that combines multiple technologies (Python, Node, Rust) into a unified product experience.

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