Fjord

Hardfork registry entry for the Fjord network upgrade, which introduced FastLZ fee estimation and Brotli compression.

Fjord improved fee estimation and batch compression, and added the secp256r1 precompile.

Status	Active
Governing spec	specs.optimism.io
Governance approval	proposal
Mainnet activation (superchain default)	Wed, 10 Jul 2024 16:00:01 UTC (1720627201)
Sepolia activation (superchain default)	Wed, 29 May 2024 16:00:00 UTC (1716998400)

What changed

Per the spec overview:

• Execution layer: RIP-7212 precompile for secp256r1 curve support; FastLZ compression for L1 data fee calculation; deprecated the getL1GasUsed method on the GasPriceOracle predeploy and the L1GasUsed receipt field.
• Consensus layer: constant maximum sequencer drift; Brotli channel compression; increased max bytes per channel and max channel bank size.