Ethereum Light Client — in your browser

This page fetches a real Ethereum block header and its sync committee aggregate signature, then verifies the BLS12-381 cryptography locally in your browser — the server is only used to fetch data, never to assert validity. The one trust assumption: a single finalized checkpoint root used to bootstrap the sync committee. After that, light client verification is fully self-contained with ~24 KB of SSZ committee state.

Library: @noble/curves (pure JS)

Trust assumption: 1 finalized checkpoint root

Data per header: ≈ 160 bytes (sig + bitfield)

Full execution block: ~100 KB–2 MB typical

spec consensus-specs/altair (Deneb-compatible)api beacon-APIs v2provider publicnode.com (mainnet beacon RPC — results depend on provider availability)last validated Apr 2026

Verification steps

Fetch genesis data

01▸

Fetch current fork version

02▸

Fetch finalized checkpoint

03▸

Fetch sync committee pubkeys

04▸

Fetch latest finality update

05▸

SSZ hash_tree_root(BeaconBlockHeader)

06▸

compute_domain(SYNC_COMMITTEE, fork, genesis)

07▸

compute_signing_root(header_root, domain)

08▸

Aggregate public keys (G1 sum of signed validators)

09▸

Hash signing_root → G2 point (hash_to_curve)

10▸

BLS pairing check: e(G1, σ) == e(pk_agg, H(m))

11▸

Result

Run verification to see the result