# Welcome

> Apache Iggy documentation: how Iggy organizes data into streams, topics, partitions and segments, and where to start.

Rendered page: https://iggy.apache.org/docs/

Source: https://github.com/apache/iggy-website/blob/main/content/docs/index.mdx

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## How Iggy organizes data

Iggy uses a hierarchical model: **streams** contain **topics**, topics contain **partitions**, and partitions store messages in **segments** on disk. This gives you flexible multi-tenancy, parallel processing, and efficient storage all in one.

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## The append-only log

Every partition is an append-only log. Messages are **immutable** once written, consumers can start from a chosen offset, and retained messages can be replayed. Retention removes old data, and offsets can contain gaps.

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## Key capabilities

| Capability | Details |
|-----------|---------|
| **Transport** | TCP, QUIC, WebSocket (custom binary protocol), HTTP (REST) |
| **Performance** | Thread-per-core + io_uring on Linux, binary message views, configurable memory pool with a default 4 GiB budget |
| **Security** | TLS on all transports, Argon2id hashing, AES-256-GCM message encryption, [granular permissions](/docs/server/security) with per-stream/per-topic permissions |
| **Connectors** | [16 sink and 4 source plugins](/docs/connectors/introduction) including PostgreSQL, MongoDB, Elasticsearch, ClickHouse, Apache Iceberg, S3, with data transforms |
| **AI Integration** | [MCP server](/docs/ai/mcp) with 40+ tools for LLM-driven message streaming management |
| **Management** | [Web UI](/docs/web_ui/start) dashboard (embedded or standalone), [CLI](/docs/cli/start) with shell completions, Prometheus metrics; connector OpenTelemetry export ([broker export limits](/docs/server/configuration#telemetry)) |
| **Clustering** | Built on [Viewstamped Replication (VSR)](/docs/clustering/vsr) consensus; single node by default, multi-node via `[cluster]` configuration |
| **Deployment** | Single server process, [Docker & Helm](/docs/server/docker), configurable CPU/NUMA affinity on Linux |

## Ecosystem

Iggy is more than just a server. The project includes a full ecosystem of tools:

- **[Connectors Runtime](/docs/connectors/introduction)** - dynamically loaded Rust plugins for data integration: 16 sinks and 4 sources. Ingest from PostgreSQL, Elasticsearch or InfluxDB into Iggy, or forward to MongoDB, Elasticsearch, ClickHouse, Apache Iceberg, Quickwit, S3 and more. Built-in data transforms and Prometheus metrics.
- **[MCP Server](/docs/ai/mcp)** - Model Context Protocol server exposing 40+ tools for LLM integration. Works with Claude Desktop via stdio and HTTP transports.
- **[Web UI](/docs/web_ui/start)** - SvelteKit dashboard for stream/topic management, message browsing with JSON/string/XML decoders, and user management.
- **[CLI](/docs/cli/start)** - full-featured command-line interface with named connection contexts, session-based login, and shell completions.
- **[SDKs](/docs/sdk/introduction)** - client libraries for 8 languages (Rust, Python, Java, Go, Node.js, C#, C++, PHP), most with runnable examples.
- **[Benchmarking](/docs/server/benchmarking)** - built-in `iggy-bench` tool with a Yew/WebAssembly dashboard for performance testing.