Introduction

What is Khedra?

Khedra (pronounced kɛd-ɾɑ) is an all-in-one blockchain indexing and monitoring solution for EVM-compatible blockchains. It provides a comprehensive suite of tools to index, monitor, serve, and share blockchain data in a local-first, privacy-preserving manner.

At its core, Khedra creates and maintains the Unchained Index - a permissionless index of address appearances across blockchain data, including transactions, event logs, execution traces, and more. This detailed indexing enables powerful monitoring capabilities for any address on any supported chain.

Key Features

1. Comprehensive Indexing

Khedra indexes address appearances from multiple sources:

Transactions (senders and recipients)
Event logs (topics and data fields)
Execution traces (internal calls)
Smart contract state changes
Block rewards and staking activities
Genesis allocations

The resulting index allows for lightning-fast lookups of any address's complete on-chain history.

2. Multi-Chain Support

While Ethereum mainnet is required, Khedra works with any EVM-compatible blockchain, including:

Test networks (Sepolia, etc.)
Layer 2 solutions (Optimism, Arbitrum)
Alternative EVMs (Gnosis Chain, etc.)

Each chain requires only a valid RPC endpoint to begin indexing.

3. Modular Service Architecture

Khedra operates through five interconnected services:

Control Service: Central management API
Scraper Service: Builds and maintains the Unchained Index
Monitor Service: Tracks specific addresses of interest
API Service: Provides data access via REST endpoints
IPFS Service: Enables distributed sharing of index data

These services can be enabled or disabled independently to suit your needs.

4. Privacy-Preserving Design

Unlike traditional blockchain explorers that track user behavior, Khedra:

Runs entirely on your local machine
Never sends queries to third-party servers
Doesn't track or log your address lookups
Gives you complete control over your data

The Unchained Index can be optionally shared and downloaded via IPFS, creating a collaborative network where:

Users can contribute to building different parts of the index
New users can download existing index portions instead of rebuilding
The index becomes more resilient through distribution

Use Cases

Khedra excels in numerous blockchain data scenarios:

Account History: Track complete transaction and interaction history for any address
Balance Tracking: Monitor native and ERC-20 token balances over time
Smart Contract Monitoring: Watch for specific events or interactions with contracts
Auditing and Accounting: Export complete financial histories for tax or business purposes
Custom Indexing: Build specialized indices for specific protocols or applications
Data Analysis: Extract patterns and insights from comprehensive on-chain data

Getting Started

The following chapters will guide you through:

Installing and configuring Khedra
Understanding the core concepts and architecture
Using the various components and services
Advanced operations and customization
Maintenance and troubleshooting

Whether you're a developer, researcher, trader, or blockchain enthusiast, Khedra provides the tools you need to extract maximum value from blockchain data while maintaining your privacy and autonomy.

Implementation Details

The core features of Khedra described in this introduction are implemented in the following Go files:

Main Application Structure: The primary application entry point is defined in main.go which initializes the KhedraApp struct defined in app/app.go.
Service Architecture Implementation:
- The service framework is initialized in app/action_daemon.go
- Service definitions and validation are in pkg/types/service.go
- Service initialization happens in the daemonAction function
Configuration System:
- Configuration loading and validation: app/config.go
- Environment variable processing: pkg/types/apply_env.go
Multi-Chain Support:
- Chain configuration and validation: app/action_init_chains.go
- RPC connection validation: pkg/validate/try_connect.go

The Khedra Book