> ## Documentation Index > Fetch the complete documentation index at: https://voltaire.tevm.sh/llms.txt > Use this file to discover all available pages before exploring further. # Hardfork Timeline > Complete list of Ethereum hardforks with dates, features, and EIP changes Run Hardfork examples in the interactive playground # Hardfork Timeline Complete list of Ethereum hardforks with dates, features, and EIP changes. ## Overview Each hardfork represents a protocol upgrade that changes EVM behavior, gas costs, or adds new features. Hardforks build upon previous ones chronologically. ```typescript theme={null} import { FRONTIER, CANCUN, PRAGUE } from 'tevm'; ``` ## Hardfork Constants All hardforks exported as constants: ```typescript theme={null} export const FRONTIER: BrandedHardfork export const HOMESTEAD: BrandedHardfork export const DAO: BrandedHardfork export const TANGERINE_WHISTLE: BrandedHardfork export const SPURIOUS_DRAGON: BrandedHardfork export const BYZANTIUM: BrandedHardfork export const CONSTANTINOPLE: BrandedHardfork export const PETERSBURG: BrandedHardfork export const ISTANBUL: BrandedHardfork export const MUIR_GLACIER: BrandedHardfork export const BERLIN: BrandedHardfork export const LONDON: BrandedHardfork export const ARROW_GLACIER: BrandedHardfork export const GRAY_GLACIER: BrandedHardfork export const MERGE: BrandedHardfork export const SHANGHAI: BrandedHardfork export const CANCUN: BrandedHardfork export const PRAGUE: BrandedHardfork export const OSAKA: BrandedHardfork export const DEFAULT: BrandedHardfork // PRAGUE ``` ## Complete Timeline ### FRONTIER (July 2015) **Original Ethereum launch** Initial release with base EVM functionality. **Key Features:** * Basic EVM opcodes (ADD, MUL, SSTORE, SLOAD, etc.) * Contract creation and execution * Mining with Ethash PoW * Gas mechanism **Status:** Foundation for all future hardforks *** ### HOMESTEAD (March 2016) **First planned hardfork** Fixed critical issues and added DELEGATECALL. **Key Features:** * `DELEGATECALL` opcode (0xF4) - Execute code in caller's context * Difficulty adjustment improvements * Gas cost changes for transaction creation * Contract creation cost changes **EIPs:** * EIP-2: Homestead hard fork changes * EIP-7: DELEGATECALL opcode *** ### DAO (July 2016) **Emergency fork for DAO hack** State-only changes, no EVM modifications. **Key Features:** * Moved funds from compromised DAO contract * No opcode or gas changes * Controversial hard fork (created Ethereum Classic split) **Status:** Historical significance, no protocol changes *** ### TANGERINE\_WHISTLE (October 2016) **Gas repricing fork** Increased gas costs for IO-heavy operations after DoS attacks. **Key Features:** * Increased gas cost for EXTCODESIZE, EXTCODECOPY, BALANCE, SLOAD * Changed gas cost for SUICIDE/SELFDESTRUCT * Maximum call depth increased **EIPs:** * EIP-150: Gas cost changes for IO-heavy operations * EIP-158: State clearing *** ### SPURIOUS\_DRAGON (November 2016) **State cleaning fork** Removed empty accounts and added replay protection. **Key Features:** * Empty account removal (state cleaning) * EXP opcode repricing * Contract code size limit (24KB) * Replay attack protection **EIPs:** * EIP-155: Simple replay attack protection * EIP-160: EXP cost increase * EIP-161: State trie clearing * EIP-170: Contract code size limit *** ### BYZANTIUM (October 2017) **Major feature fork** Added important opcodes for smart contract functionality. **Key Features:** * `REVERT` opcode (0xFD) - Revert with error message * `RETURNDATASIZE` (0x3D) and `RETURNDATACOPY` (0x3E) * `STATICCALL` opcode (0xFA) - Non-state-changing calls * Modified difficulty adjustment (ice age delay) * zkSNARK precompiles **EIPs:** * EIP-140: REVERT instruction * EIP-211: RETURNDATASIZE and RETURNDATACOPY * EIP-214: STATICCALL opcode * EIP-658: Embedding transaction status in receipts * EIP-196: zkSNARK precompile (alt\_bn128 addition) * EIP-197: zkSNARK precompile (alt\_bn128 multiplication) * EIP-198: BigInt modular exponentiation precompile *** ### CONSTANTINOPLE (February 2019) **Efficiency improvements** Added CREATE2 and bitwise shift opcodes. **Key Features:** * `CREATE2` opcode (0xF5) - Deterministic contract addresses * `SHL` (0x1B), `SHR` (0x1C), `SAR` (0x1D) - Bitwise shift operators * `EXTCODEHASH` opcode (0x3F) - Get contract code hash * Gas cost optimizations **EIPs:** * EIP-1014: CREATE2 opcode (Skinny CREATE2) * EIP-145: Bitwise shifting instructions * EIP-1052: EXTCODEHASH opcode * EIP-1234: Constantinople difficulty bomb delay *** ### PETERSBURG (February 2019) **Quick fix fork** Removed EIP-1283 due to reentrancy concerns. Deployed simultaneously with Constantinople after delay. **Key Features:** * Removed EIP-1283 (net gas metering for SSTORE) * All other Constantinople features retained **EIPs:** * EIP-1283: Removed (was net gas metering for SSTORE) **Note:** Petersburg = Constantinople - EIP-1283 *** ### ISTANBUL (December 2019) **Gas optimization fork** Rebalanced SSTORE gas costs and added new opcodes. **Key Features:** * `CHAINID` opcode (0x46) - Get current chain ID * `SELFBALANCE` opcode (0x47) - Get contract's own balance (cheaper than BALANCE) * SSTORE gas cost rebalancing (EIP-2200) * Gas cost reductions for SNARKs and STARKs * Blake2 compression precompile **EIPs:** * EIP-152: Blake2 precompile * EIP-1108: Reduce alt\_bn128 precompile gas costs * EIP-1344: CHAINID opcode * EIP-1884: Repricing for trie-size-dependent opcodes * EIP-2028: Calldata gas cost reduction * EIP-2200: Net gas metering for SSTORE (reintroduced safely) *** ### MUIR\_GLACIER (January 2020) **Difficulty bomb delay** Delayed ice age, no EVM changes. **Key Features:** * Difficulty bomb delayed 4,000,000 blocks * No opcode changes * No gas cost changes **EIPs:** * EIP-2384: Muir Glacier difficulty bomb delay **Status:** Administrative fork, no protocol changes *** ### BERLIN (April 2021) **Access list fork** Gas cost changes for state access patterns. **Key Features:** * Cold/warm storage access distinction * Increased gas costs for SLOAD, *CALL, BALANCE, EXT* operations on first access * Optional access lists in transactions (Type 1) * `MODEXP` precompile gas cost changes **EIPs:** * EIP-2565: ModExp gas cost * EIP-2718: Typed transaction envelope * EIP-2929: Gas cost increases for state access opcodes * EIP-2930: Optional access lists **Impact:** Changed gas costs for many operations *** ### LONDON (August 2021) **Fee market reform** Introduced EIP-1559 base fee mechanism. **Key Features:** * **EIP-1559**: Base fee + priority fee transaction pricing * `BASEFEE` opcode (0x48) - Get current block's base fee * Base fee burned (deflationary mechanism) * Type 2 transactions (EIP-1559) * Ice age delay **EIPs:** * EIP-1559: Fee market change for ETH 1.0 chain * EIP-3198: BASEFEE opcode * EIP-3529: Reduction in refunds * EIP-3541: Reject new contracts starting with 0xEF * EIP-3554: Difficulty bomb delay **Impact:** Fundamental change to transaction fee mechanism *** ### ARROW\_GLACIER (December 2021) **Difficulty bomb delay** Delayed ice age before Merge, no EVM changes. **Key Features:** * Difficulty bomb delayed \~6 months * No opcode changes * No gas cost changes **EIPs:** * EIP-4345: Difficulty bomb delay **Status:** Administrative fork preparing for Merge *** ### GRAY\_GLACIER (June 2022) **Difficulty bomb delay** Further delayed ice age before Merge, no EVM changes. **Key Features:** * Difficulty bomb delayed 700,000 blocks * No opcode changes * No gas cost changes **EIPs:** * EIP-5133: Difficulty bomb delay **Status:** Final delay before Merge *** ### MERGE (September 2022) **Proof of Stake transition** Historic transition from Proof of Work to Proof of Stake. **Key Features:** * **Proof of Stake consensus** - No more mining * `PREVRANDAO` opcode (replaces DIFFICULTY, still 0x44) * Beacon chain integration * DIFFICULTY opcode returns PREVRANDAO value * Block structure changes **EIPs:** * EIP-3675: Upgrade consensus to Proof of Stake * EIP-4399: Supplant DIFFICULTY with PREVRANDAO **Aliases:** "Paris" (consensus layer name) **Impact:** Fundamental change from PoW to PoS *** ### SHANGHAI (April 2023) **Withdrawal enabling fork** Enabled staking withdrawals and added PUSH0. **Key Features:** * **EIP-3855**: `PUSH0` opcode (0x5F) - Push constant 0 onto stack * Staking withdrawals enabled * Warm COINBASE (EIP-3651) **EIPs:** * EIP-3651: Warm COINBASE * EIP-3855: PUSH0 instruction * EIP-3860: Limit and meter initcode * EIP-4895: Beacon chain push withdrawals **Impact:** Enabled staking withdrawals, gas savings with PUSH0 *** ### CANCUN (March 2024) **Proto-danksharding fork** Introduced blob transactions for L2 scalability. **Key Features:** * **EIP-4844**: Blob transactions (Type 3) - Proto-danksharding * `BLOBHASH` opcode (0x49) - Access blob versioned hashes * `BLOBBASEFEE` opcode (0x4A) - Get blob gas base fee * **EIP-1153**: Transient storage - `TLOAD` (0x5C) and `TSTORE` (0x5D) * **EIP-5656**: `MCOPY` opcode (0x5E) - Memory copy instruction * Point evaluation precompile for KZG commitments **EIPs:** * EIP-1153: Transient storage opcodes (TLOAD/TSTORE) * EIP-4844: Shard blob transactions (proto-danksharding) * EIP-4788: Beacon block root in EVM * EIP-5656: MCOPY instruction * EIP-6780: SELFDESTRUCT only in same transaction * EIP-7516: BLOBBASEFEE opcode **Impact:** Major scalability improvement for L2s via cheap blob data *** ### PRAGUE (May 2025) **Prague-Electra fork** Current default. BLS cryptography and account abstraction features. **Key Features:** * **EIP-2537**: BLS12-381 curve precompiles (10 new precompiles) * **EIP-7702**: Set EOA code for one transaction (account abstraction) * Validator set changes (EIP-7251, EIP-7002) * MaxEB (Maximum effective balance increase) **EIPs:** * EIP-2537: BLS12-381 curve operations precompiles * EIP-7002: Execution layer triggerable exits * EIP-7251: Increase max effective balance * EIP-7702: Set EOA account code for one transaction * EIP-2935: Serve historical block hashes from state **Status:** Current default hardfork **Impact:** Enables native account abstraction patterns, BLS signatures *** ### OSAKA (TBD) **Future fork** Planned improvements to ModExp and transaction limits. **Key Features:** * **EIP-7883**: ModExp gas increase for large inputs * EIP-7823: ModExp upper bounds * Transaction and block limits **EIPs:** * EIP-7883: ModExp gas increase * EIP-7823: ModExp upper bounds * EIP-7825: Transaction gas limit cap * EIP-7934: Block RLP limit **Status:** Planned, not yet deployed *** ## Summary Tables ### Consensus Changes | Hardfork | Consensus | Change | | ----------------------- | -------------- | ----------------------- | | Frontier - Gray Glacier | Proof of Work | Ethash mining | | Merge+ | Proof of Stake | Beacon chain validators | ### Major Opcode Additions | Hardfork | Opcodes | Purpose | | -------------- | -------------------------------- | ------------------------------- | | Homestead | DELEGATECALL | Execute in caller context | | Byzantium | REVERT, STATICCALL | Error handling, view functions | | Constantinople | CREATE2, SHL/SHR/SAR | Deterministic addresses, shifts | | Istanbul | CHAINID, SELFBALANCE | Chain ID, gas optimization | | London | BASEFEE | EIP-1559 base fee | | Merge | PREVRANDAO (replaces DIFFICULTY) | PoS randomness | | Shanghai | PUSH0 | Gas savings | | Cancun | TLOAD/TSTORE, MCOPY, BLOBHASH | Transient storage, blobs | ### Feature Timeline | Feature | Hardfork | EIP | | ----------------- | -------------- | -------- | | DELEGATECALL | Homestead | EIP-7 | | REVERT | Byzantium | EIP-140 | | STATICCALL | Byzantium | EIP-214 | | CREATE2 | Constantinople | EIP-1014 | | CHAINID | Istanbul | EIP-1344 | | Access Lists | Berlin | EIP-2930 | | EIP-1559 | London | EIP-1559 | | Proof of Stake | Merge | EIP-3675 | | PUSH0 | Shanghai | EIP-3855 | | Blob Transactions | Cancun | EIP-4844 | | Transient Storage | Cancun | EIP-1153 | | BLS Precompiles | Prague | EIP-2537 | ## Usage ```typescript theme={null} import { FRONTIER, HOMESTEAD, BYZANTIUM, CONSTANTINOPLE, ISTANBUL, BERLIN, LONDON, MERGE, SHANGHAI, CANCUN, PRAGUE, OSAKA, DEFAULT } from 'tevm'; // Use constants directly console.log(CANCUN); // "cancun" // Compare versions import { isAtLeast } from 'tevm'; isAtLeast(CANCUN, LONDON); // true // Check features import { hasEIP4844 } from 'tevm'; hasEIP4844(CANCUN); // true hasEIP4844(SHANGHAI); // false ``` ## Related * [features.mdx](./features.mdx) - Feature detection methods * [comparisons.mdx](./comparisons.mdx) - Version comparison * [index.mdx](./index.mdx) - Main documentation