Ethereum’s historic transition—The Merge—has already taken place, marking a pivotal shift from energy-intensive proof-of-work (PoW) to a more sustainable, secure, and scalable proof-of-stake (PoS) consensus mechanism. If you're using Chainstack, your infrastructure seamlessly adapted to this change with zero downtime and no action required on your part.
This guide breaks down everything developers need to know about The Merge, including its technical implications, impact on smart contracts and DApps, changes in block structure, and the future of Ethereum testnets.
Understanding The Merge: Ethereum’s Shift to Proof-of-Stake
The Merge refers to the integration of Ethereum’s original Execution Layer (formerly known as Mainnet) with its new Consensus Layer—the Beacon Chain. This event, completed on September 15, 2022, marked Ethereum’s official move from PoW to PoS.
With this transition:
- Energy consumption dropped by over 99%
- Network security is now maintained by validators who stake ETH
- The foundation is laid for future scalability upgrades like sharding
For developers, the change was largely invisible at the application layer—but not entirely without consequence.
👉 Discover how modern blockchain infrastructure simplifies post-Merge development.
Key Changes for Developers After The Merge
While most DApp and smart contract logic remains unaffected, several technical updates require awareness to ensure long-term compatibility.
Block Structure Evolution
After The Merge, PoW blocks were incorporated into the new PoS block format generated by the Beacon Chain. The Execution Layer clients—such as Geth, Erigon, Besu, and Nethermind—still process transactions, meaning your existing API calls (e.g., eth_sendTransaction, eth_call) remain unchanged.
However, the underlying block headers now reflect PoS logic.
Elimination of Ommers (Uncle Blocks)
In PoW, orphaned blocks—called ommers or uncle blocks—were common due to network competition. PoS eliminates this concept entirely.
As a result:
- The
ommersfield is now an empty list ommersHashbecomes an RLP-encoded hash of an empty listdifficultyandnoncefields are set to0
These values are preserved for backward compatibility but carry no functional weight.
Opcode Updates: BLOCKHASH and PREVRANDAO
Two critical opcodes have evolved:
- BLOCKHASH: Still available but provides weaker pseudo-randomness under PoS due to predictable block intervals.
- DIFFICULTY (0x44): Renamed to PREVRANDAO, it now returns a verifiable random value derived from the Beacon Chain’s randomness beacon—making it a superior source of on-chain randomness.
👉 Leverage secure, high-performance nodes for reliable access to PREVRANDAO and other PoS features.
Reduced and Predictable Block Time
Under PoW, average block time hovered around 13 seconds. Post-Merge, Ethereum enforces a fixed 12-second slot time, with only ~1% of slots expected to be missed due to validator latency or downtime.
Implication for developers: Smart contracts relying on time-based logic (e.g., auctions, vesting schedules) should account for this ~1-second reduction to avoid miscalculations.
Introduction of Safe Head and Finalized Blocks
One of the most significant improvements is enhanced finality through two new block types:
- Safe Head: A block that cannot be reorged under normal conditions (network delay < 4 seconds, honest majority). It represents the current tip of the chain with high confidence.
- Finalized Block: A block ratified by at least ⅔ of validators, making it nearly attack-proof. Reversing it would require burning ⅓ of total staked ETH—currently equivalent to billions of dollars.
Chainstack’s Execution Layer APIs expose these via _safe_ and _finalized_ tags, enabling applications to programmatically confirm transaction finality with greater precision than ever before.
How Node Operators Were Affected—And Why Chainstack Simplified It
Running a node through The Merge required significant coordination. Operators had to:
- Run both a consensus layer client (e.g., Prysm, Lighthouse) and an execution layer client
- Connect them via the Engine API, secured with a shared JWT secret
- Migrate off deprecated testnets like Ropsten and Rinkeby
With Chainstack, none of this was necessary. We managed all infrastructure updates seamlessly, ensuring continuous uptime across Mainnet and supported testnets.
You continued building—without interruptions.
What Happened to Ethereum Testnets?
To reduce maintenance overhead and streamline testing, the Ethereum community decided to consolidate around two primary testnets post-Merge: Goerli and Sepolia.
Legacy networks—Kiln, Ropsten, and Rinkeby—are being phased out.
Testnet Shutdown Overview
- Kiln: Successfully merged in March 2022; no longer supported.
- Ropsten: Merged June 8, 2022; support ended Q4 2022.
- Rinkeby: Did not merge; support discontinued Q3–Q4 2023.
- Goerli: Merged August 10, 2022; fully supported.
- Sepolia: Merged July 6, 2022; now supported on Chainstack.
Choosing Between Goerli and Sepolia
| Use Case | Recommended Testnet |
|---|---|
| Testing protocol upgrades before Mainnet deployment | Goerli |
| Fast node syncing and lower storage requirements | Sepolia |
Goerli mirrors Mainnet closely in state and ecosystem maturity. Sepolia, being newer, offers faster sync times and lighter resource demands—ideal for rapid development cycles.
Common Misconceptions About The Merge
Let’s clear up widespread myths:
❌ You can withdraw staked ETH after The Merge
False. Withdrawals were enabled months later via the Shanghai upgrade in April 2023.
❌ The Merge reduces gas fees
False. Throughput remains capped at ~15 TPS. For lower fees and higher throughput, use Layer 2 solutions like Optimism or zkSync.
✅ The Merge reduces ETH issuance
True. New ETH issuance dropped by approximately 90%, contributing to a more deflationary economic model.
🤨 The Merge requires app updates
Partially true. Most DApps don’t need changes—but those using block difficulty or time-sensitive logic should adapt.
❌ You need 32 ETH to run a node
False. You need 0 ETH to run a non-validator node. Only validator nodes require a 32 ETH stake.
Frequently Asked Questions (FAQs)
What is The Merge?
The Merge refers to the integration of Ethereum’s Execution Layer (Mainnet) with the Beacon Chain as its new Consensus Layer, transitioning the network from proof-of-work to proof-of-stake.
Is the Beacon Chain a separate blockchain?
Yes. It’s a standalone PoS chain that coordinates validators but doesn’t process transactions or execute smart contracts.
What are the benefits of The Merge?
It makes Ethereum more energy-efficient (99%+ reduction), secure through economic finality, and sets the stage for future scalability upgrades.
When did The Merge happen?
Ethereum completed The Merge on September 15, 2022.
Do I need to update my DApp?
No immediate action is needed—but ensure your smart contracts account for the new 12-second block time and prefer PREVRANDAO over BLOCKHASH for randomness.
Why are some testnets being shut down?
To reduce fragmentation and maintenance costs, the community consolidated testing on Goerli and Sepolia.
Final Thoughts: Build Confidently on Post-Merge Ethereum
The Merge wasn’t just a consensus upgrade—it was a foundational transformation that redefined Ethereum’s sustainability and security model. For developers, the transition was smooth, especially when leveraging robust infrastructure platforms like Chainstack.
Now that legacy testnets are retired and PoS is fully operational, focus shifts to building resilient, scalable applications using modern tools and best practices.
👉 Access reliable Ethereum nodes built for the PoS era—start building today.
Whether you're deploying smart contracts, integrating wallet services, or building decentralized exchanges, understanding The Merge ensures your projects remain future-proof in Ethereum’s evolving ecosystem.