Blobs
Blobs are large binary data chunks rollups attach to Ethereum blocks since EIP-4844 — up to ~128 KB each, priced on their own fee market, and auto-deleted
Blobs are large binary data chunks rollups attach to Ethereum blocks since EIP-4844 — up to ~128 KB each, priced on their own fee market, and auto-deleted after about 18 days. They’re how L2s publish transaction data without paying L1 execution prices.
How it works
A rollup bundles thousands of L2 transactions, posts the bundle as blob data, and references it from an L1 transaction. Consensus nodes hold blobs just long enough for fraud/validity verification; then they’re pruned to keep node requirements low. Indexers and the rollups themselves keep permanent copies for explorers.
Why it matters for decentralization
Blobs are the price mechanism that keeps settlement decentralized: if posting data to Ethereum cost 10x more, rollups would retreat to trusted data committees. Cheap on-chain availability preserves the “verify, don’t trust” property for anyone running a node.
Risks & trade-offs
Fixed blob space means congestion returns under heavy demand; pruned history centralizes archival power in a few indexers; and blob-fee spikes can still freeze small rollups out during manias.
FAQ
Blobs vs calldata? Calldata lives forever and costs execution-gas prices; blobs are temporary and ~10x cheaper — purpose-built for rollup data.
Who stores blobs long-term? Rollup teams, explorers, and archivists — not the protocol. Verify-then-prune is the whole design.
Can blob fees spike? Yes — EIP-4844 added a separate fee market that also gets expensive when blob demand exceeds supply.
Related terms
EIP-4844 ·
data availability · rollup ·
proto-danksharding