> ## Documentation Index
> Fetch the complete documentation index at: https://docs.base.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Fjord

> Overview of the Fjord hardfork, introducing FastLZ-based L1 fee estimation, the RIP-7212 secp256r1 precompile, and brotli channel compression.

## Activation Timestamps

| Network   | Activation timestamp                   |
| --------- | -------------------------------------- |
| `mainnet` | `1720627201` (2024-07-10 16:00:01 UTC) |
| `sepolia` | `1716998400` (2024-05-29 16:00:00 UTC) |

## Execution Layer

* [RIP-7212: Precompile for secp256r1 Curve Support](/base-chain/specs/protocol/execution/evm/precompiles#P256VERIFY)
* [FastLZ compression for L1 data fee calculation](/base-chain/specs/upgrades/fjord/exec-engine#fees)
* [Deprecate the `getL1GasUsed` method on the `GasPriceOracle` contract](/base-chain/specs/upgrades/fjord/predeploys#l1-gas-usage-estimation)
* [Deprecate the `L1GasUsed` field on the transaction receipt](/base-chain/specs/upgrades/fjord/exec-engine#l1-gas-usage-estimation)

## Consensus Layer

* [Constant maximum sequencer drift](/base-chain/specs/upgrades/fjord/derivation#constant-maximum-sequencer-drift)
* [Brotli channel compression](/base-chain/specs/upgrades/fjord/derivation#brotli-channel-compression)
* [Increase Max Bytes Per Channel and Max Channel Bank Size](/base-chain/specs/upgrades/fjord/derivation#increasing-max_rlp_bytes_per_channel-and-max_channel_bank_size)