Ethereum Consensus Explorer

An interactive block explorer for Ethereum's consensus layer (the Beacon Chain). Enter a slot number, or view the chain head, and inspect the block: its proposer, state and parent roots, attestations, and finality status, fetched live from a public Beacon Node API.

Built from scratch in vanilla JavaScript, no frameworks.

Live demo

What it does

• Live beacon data: pulls real blocks from the Ethereum Beacon Chain in real time via the standard Beacon Node API.
• Slot lookup: search any slot by number (head or historical), or load the chain head by default.
• Block detail: displays slot, proposer index, parent root, state root, and the block's attestations with their committee indices.
• Finality status: shows whether a block is finalized or still pending, reflecting the finality lag between the chain head and the last finalized checkpoint.
• Graceful errors: skipped or missing slots (which have no block) are handled without crashing.

How it works

The app is a single HTML file with plain JavaScript. On load, and on each search, it:

1. Reads the requested slot from the input (defaulting to head).
2. Fetches the block from /eth/v2/beacon/blocks/{slot} on a public Beacon Node API.
3. Parses the response and renders the block detail and attestations directly to the DOM.

No build step, no dependencies. The data source is a public consensus-layer endpoint, so no node or API key is required to run it.

Running locally

Because the app makes network requests, serve it over HTTP rather than opening the file directly (the file:// protocol blocks fetch):

# from the project folder
python3 -m http.server 8000

Then open http://localhost:8000 in your browser.

Tech

• Vanilla JavaScript (fetch, async/await, DOM rendering)
• HTML / CSS
• Ethereum Beacon Node API

Roadmap

This is an active project. Planned additions, in rough order:

• Deploy a live version
• Full finality detail via the finality-checkpoints endpoint (justified vs. finalized)
• Light-client data view: sync committee and Merkle-proof inspection
• Rust backend (Axum/Tokio) for data ingestion and caching
• React + TypeScript frontend

Context

I'm an Ethereum Foundation Protocol Fellow working on trust-minimized checkpoint sync for Ethereum's consensus layer (light client protocol and Merkle proofs, in Rust). This explorer is a tool for visualizing and interacting with the consensus-layer data that work is built on.