Introduction to “Testnets” (Goerli, Sepolia)

You’re right in the thick of user-acceptance testing when disaster strikes: your Goerli pipeline crashes. You’re dealing with rate limits from the faucets, RPCs that have been shut down, and those pesky L2 “-goerli” endpoints that just aren’t playing nice, throwing 404 errors your way. Your release plan was built on the idea of having a solid pre-prod chain, but with Goerli winding down and L2s already shifting their testnets over to Sepolia, things are getting a bit tricky.

Key updates Enterprise teams need to keep in mind today:
- Ethereum app testing has officially shifted to Sepolia (chainId 11155111). Check it out here: (ethereum.org).
- Goerli support was pretty much phased out across L1/L2s in the first half of 2024; many providers turned off Goerli RPCs around or right after April 1, 2024. You can find more details at (alchemy.com).
- Holesky, which was great for validator-scale testing, got the axe in 2025; now, Hoodi has taken the spotlight as the go-to testnet for validators and staking. Developers should definitely stick with Sepolia for their applications. For more info, check this out: (blog.ethereum.org).

If your pre-production relies on Goerli, the risks are pretty real. We're talking about missed deadlines, slipping audit schedules, and having to redo procurement when vendors can’t stick to their service level agreements on an outdated network.

Agitate: What’s at stake if you don’t switch

Missed deadlines and QA drift
- So, the L2s--like Optimism, Arbitrum, and Base--have officially retired “-goerli” and are now all about OP/Arbitrum/Base Sepolia. If you haven't updated your integration tests and bridges, get ready for some failures. Check this out for more info: (alchemy.com).
Faucet friction and team throughput loss
- Ever since Goerli ETH became a hot commodity in 2023, faucets have been pretty unreliable and are often rate-limited. This has really put a damper on our test cycles and onboarding processes. More details can be found here: (blockworks.co).
Compliance and vendor risk
- Heads up! Procurement is going to be asking for SOC2, uptime SLAs, region pinning, and data-handling attestations. A bunch of infrastructure vendors have updated their policies for the Sepolia testnets, like Chainstack getting their SOC 2 Type II. You can read more about it here: (chainstack.com).
Cost modeling mismatch post-Dencun
- With EIP-4844 (Dencun) coming into play, L2 costs have taken a nosedive--around 90-98% cheaper thanks to blob transactions. It's crucial to recalibrate your gas budgets, fee alerts, and unit-economics models on the Sepolia and L2 sepolia testnets. For further insights, check this link: (blog.ethereum.org).

The result? Longer test cycles, off-the-mark performance and cost predictions, and postponed production rollouts.

7Block Labs’ pragmatic migration playbook (Solidity, ZK, AA) to Sepolia

We see testnets as essential pre-production environments--reliable, repeatable, and ready for audits--rather than just “toy chains.” Here’s our game plan for smoothly transitioning away from Goerli and standardizing on Sepolia, along with downstream L2s, all while keeping in line with Enterprise security and procurement standards.

1) Network strategy: where each workload belongs

App and tooling testing: Sepolia only
- ChainId 11155111 is the go-to here. It has solid support from explorers like Etherscan and Otterscan, plus a robust faucet ecosystem. You can find more info at chainid.network.
Validator/staking/protocol testing: Hoodi (taking over from Holesky)
- Just a heads-up, Holesky will be winding down on September 1, 2025. Hoodi is set up for validator lifecycles and protocol upgrades, but you shouldn’t count on it for app testing. For further details, check out the announcement on blog.ethereum.org.
L2 testnets (to mimic your mainnet L2 footprint)
- Explore options like OP Sepolia, Arbitrum Sepolia, Base Sepolia, and others. Make sure your L2 endpoints are in sync with L1 Sepolia so you’ve got smooth deposits, withdrawals, and bridge flows. More info can be found at ethereum.org.

Implementation Note

Make sure to update your chain registry (like Chainlist or chainid.network) and your infrastructure code to include Sepolia along with the relevant L2-Sepolia chain IDs, explorers, and RPCs. You can find more details here: (chainid.network).

2) RPC and vendor selection: evidence for Procurement

What we look for:
- SOC2 or something similar (Type II is a plus), 99.99%+ uptime, availability in global regions, clear rate-limit info, and a history of incidents.
Some examples of what we've found:
- Chainstack: They have SOC 2 Type II certification (valid until Dec 2025) and promote their 99.99%+ uptime. Check it out here: (chainstack.com).
- QuickNode: They mention their SOC2 certification in their enterprise positioning (just a heads up, procurement will still ask for a report under NDA). More details here: (blog.quicknode.com).
Why does all this matter? Well, "SOC2" is becoming a key term in RFPs, which means it can really streamline the process and cut down on security questionnaire rounds. Plus, it jives with vendor risk policies. We’ll take care of the RFI/RFP prep and ensure all controls align with your MSA/SLA.

3) Faucets without drama

If you’re looking for a reliable way to get some daily ETH, the Google Cloud Web3 Faucet (Sepolia) is a solid choice. It’s great for those predictable drips. You can also top up your balance with faucets from Chainstack and QuickNode if you need a little extra. Check it out here: (cloud.google.com)
It’s best to steer clear of social-only faucets for your CI needs. Opt for options that use a provider or API key to keep your throughput steady. Just a heads up, Ethereum.org has an updated list of Sepolia faucets if you want to explore more. (ethereum.org)
Here are some operational guardrails to keep everything running smoothly:
- Make sure to budget for your test ETH demand and pre-warm your project wallets every week.
- Set up an internal “faucet proxy” microservice with some rate-limit backoff and retry policies to stay on top of things.

4) DevSecOps: deterministic environments over public-testnet randomness

To ensure your testing is both reproducible and aligned with SOC2 standards, consider enhancing Sepolia with the following options:
- Use mainnet-forked local chains for important flows--think Foundry or Anvil, or even Hardhat. Both Anvil and Foundry can track gas usage to help you spot any regressions. Check it out here.
- Implement virtual testnets like Tenderly Virtual TestNets to sidestep those annoying faucet delays and keep everyone on the same page with stable states. They work great with Sepolia-based forks, offering an “unlimited faucet” and state syncing capabilities. More info can be found here.

Why: Using Sepolia parity for integration tests makes sense because it allows you to run tests in a stable environment. Meanwhile, for performance, data-seeding, and edge cases, you can use forked or virtual networks that don’t have the restrictions that come with public infrastructure.

5) Gas and cost realism in the Dencun era

After Dencun, L2 fees took a nosedive, dropping by around 90-98% across the board (Base, OP Mainnet, Starknet). This drop is mainly due to EIP-4844’s blob pricing, which is different from typical calldata. Make sure your cost dashboards and alerts are updated to reflect these new blob gas dynamics. (thedefiant.io)
Here’s what you need to do:
- Change your test networks to “-sepolia” L2s so your fee telemetry tracks those blob-backed batches.
- Utilize Foundry’s gas report in your CI (just run forge test --gas-report) and check for snapshot diffs; also, set limits per PR to keep those regressions at bay. (learnblockchain.cn)

6) Account Abstraction (EIP-4337) on Sepolia

If you're working with smart accounts, make sure to double-check the Entrypoint addresses for each network. For Sepolia, here are the common Entrypoint versions you’ll want to note:
- v0.6: 0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789
- v0.7: 0x0000000071727De22E5E9d8BAf0edAc6f37da032 (docs.pimlico.io)
Here’s what you need to do:
- Update your bundler URLs to point to the Sepolia versions (think Pimlico/Stackup) and check that paymasters are set to fund test gas with clear limits in CI.
- Regenerate the AA signing keys for your test tenants, and make sure that your KMS/HSM policies match those in production.

7) ZK workflows: run verifiers on Sepolia

Practical Pattern:
- Start by proving off-chain using Halo2, Plonk, or whatever system you're working with. Then, test your verification on Sepolia with a deployed verifier contract. Don't forget to simulate the whole process on your target L2 Sepolia as well!
Why Sepolia Now:
- Sepolia is a solid choice because it keeps pace with the mainnet EVM behavior and any upgrades. For instance, we've seen Dencun make its way through Goerli, then to Sepolia, and later to Holesky before hitting the mainnet in 2024. This means your verifier and calldata patterns will stay relevant! Check it out here: blog.ethereum.org

Hands-on examples your team can lift-and-ship

Here are some handy implementation snippets that we standardize in our Enterprise pipelines. They’re designed to be straightforward--just plug them into your Makefiles or GitHub Actions to make the migration process smoother and less risky.

A) One-time cutover: env, deploy, and verify on Sepolia

Network constants (make sure to validate this once in CI):

# Confirm Sepolia chain id in CI to prevent network mismatches
cast chain-id --rpc-url "$SEPOLIA_RPC"  # expect 11155111

Foundry project configuration:

# foundry.toml
[profile.default]
src = 'src'
out = 'out'
libs = ['lib']
evm_version = 'cancun'
optimizer = true
optimizer_runs = 2_000

[rpc_endpoints]
sepolia = "${SEPOLIA_RPC}"

[etherscan]
sepolia = { key = "${ETHERSCAN_API_KEY}" }

# Gas visibility in CI
gas_reports = ["*"]

Deployment and Verification:

# Deploy to Sepolia
forge create src/MyContract.sol:MyContract \
  --rpc-url "$SEPOLIA_RPC" \
  --private-key "$DEPLOYER_PK" \
  --verify --etherscan-api-key "$ETHERSCAN_API_KEY"

# Enforce gas ceilings per function via CI checks
forge test --gas-report | tee gas.txt
grep -E "MyContract\s+myHotPath\s+avg\s+([0-9]{1,6})" gas.txt \
  | awk '{ if ($4 > 90000) exit 1 }'

Why this matters: “Gas ceilings” quickly fall short when it comes to performance regressions, helping ensure that budgets stay in line with the new post-Dencun economic landscape.

B) Fork mainnet for reproducible hot-path tests (no faucet wait)

# Use Anvil to fork mainnet for a reproducible test sandbox
anvil --fork-url "$MAINNET_RPC" --chain-id 1 --block-time 12 --steps-tracing
# In another shell, run:
forge test --fork-url "http://127.0.0.1:8545" --match-test testCriticalFlow --gas-report

This keeps your performance-sensitive tests separate from any variability on the public testnet, while your integration flows continue to run on Sepolia.

C) Bridge ETH from Sepolia to OP Sepolia (Superchain)

If you're diving into development, the docs suggest using the Superchain Bridges UI/SDK to bridge from Sepolia to OP Sepolia. Plus, CI tooling can tap into those same bridges for your end-to-end testing. Check it out here: (docs.optimism.io)

Operational Tip:

Set up your deposits to run during a nightly job. This way, your CI won’t be held up waiting for bridge finality.

D) Account Abstraction (EIP-4337) quick-start on Sepolia

// Pseudocode: sponsor transactions via a paymaster on Sepolia
const entryPoint = "0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789"; // v0.6 on Sepolia
// assemble userOp, send to your bundler endpoint (Sepolia)

Make sure to check the Entrypoint versions with your bundler provider to steer clear of any mismatches when you're going through audits. You can find more details here.

Emerging best practices we apply on every Enterprise engagement

Separate concerns: Use Sepolia to make sure your app is running smoothly, while forks and virtual testnets can help with performance testing, data seeding, and chaos drills. Tenderly Virtual TestNets are great because they offer an “unlimited faucet,” state sync, and private explorers--perfect for regulated teams that need a controlled, audit-friendly pre-production environment. (tenderly.co)
Validate upgrade cadence: Keep an eye on Dencun; it hit Sepolia on January 30, 2024 (epoch 132608) before going to mainnet. You can expect a similar rollout for future forks, so set up alerts for EF testnet announcements. (blog.ethereum.org)
Treat faucets like dependencies: Make sure to monitor their status and rate limits. Always have at least two backup options (like Google Cloud and Chainstack) to prevent any CI hiccups. (cloud.google.com)
L2 alignment: Double-check that your L2 testnets are the “-sepolia” versions (like OP, Arbitrum, and Base). This way, you can effectively test blob-based fee paths and bridge logic that resembles the production environment. (alchemy.com)
Compliance by construction: Create a shortlist of SOC2-capable infrastructure partners to speed up your RFP cycles. If certain reports are held back (thanks to an NDA), start those request chains early. Chainstack's SOC 2 Type II certification is a solid indicator for procurement decisions. (chainstack.com)

Prove: outcomes and GTM metrics tied to the migration

Time-to-Mainnet
- By consolidating pre-production work on Sepolia along with using forked or virtual networks, we can really speed up user acceptance testing (UAT) and regression cycles. This approach helps us dodge those frustrating faucet bottlenecks and Goerli breakages. Plus, the L2-sepolia bridges reflect production finality, which helps minimize those “last-mile surprises.”
Cost accuracy
- After the Dencun update, the blob economics we see in L2 Sepolia networks are super telling. If we shift our test coverage there, we can get fee telemetry that’s only a few percent off from what we see in production trends. Public analyses indicate that L2 fees have dropped by 90-98% post-Dencun, so make sure your unit-economics modeling lines up with that reality. (thedefiant.io)
Security and Procurement velocity
- Opting for vendors that have a SOC2 posture and published uptime stats can make life a whole lot easier when filling out vendor questionnaires and negotiating SLAs. For instance, Chainstack proudly showcases its SOC 2 Type II certification and a 99.99%+ uptime, while QuickNode boasts its own SOC2 certification. While these claims don’t eliminate the need for due diligence, they sure do speed things up. (chainstack.com)
Reliability of pipeline signals
- When we pair Sepolia with Virtual TestNets (think state sync and unlimited faucet access), we end up with deterministic test data. This setup allows us to pinpoint defects more quickly and reduces false negatives in continuous integration, which is crucial for hitting our quarterly release goals. (tenderly.co)

7Block Labs methodology: from RFP to production cutover

Architecture and Network Plan
- Let's map out every workload to Sepolia, L2 Sepolia, and Hoodi, making sure we include clear SLAs, explorers, and RPCs. We’ll codify everything in our Infrastructure as Code and CI templates.
DevSecOps Enablement
- We need to standardize the Foundry and Hardhat stacks with gas reporting, mainnet forks, and deterministic data loads. On top of that, let's add some Virtual TestNets for the team so we can collaborate and run performance tests without worrying about faucet limitations. (learnblockchain.cn)
Compliance Packaging
- It’s time to prepare SOC2-focused vendor packages for Procurement. This will include uptime and region attestations, along with incident handling playbooks. Our goal is to align your internal controls with vendor artifacts to speed up the sign-off process.
ZK and AA Implementation
- We need to get verifiers rolled out to Sepolia, bundle the EIP-4337 flows with the right Entrypoint versions, and test the L2 blob fee paths on the “-sepolia” networks. (docs.pimlico.io)
Cutover & KPI Tracking
- Let's keep an eye on key metrics like deploy lead time, defect escape rates, gas budget variances, faucet-related test failures, and bridge failure MTTR. We can link our improvements to ROI when presenting to the steering committee.

Where we come in:

Looking for a complete delivery solution? Check out our custom blockchain development services, web3 development services, and smart contract development.
Need a security check and ready to launch? Our security audit services are perfect for validating your Sepolia/L2-sepolia deployments before going live on the mainnet.
Got complex integrations or L2 bridges on your mind? We’ve got you covered with our blockchain integration, cross-chain solutions development, and blockchain bridge development.
Want a complete dApp stack? Dive into our dApp development and DeFi development services.

Quick reference: current testnet landscape you can trust

If you're diving into application testing, you'll want to check out Sepolia. It's got a chainId of 11155111 and you can keep an eye on things at the explorer: sepolia.etherscan.io. Plus, it has a permissioned validator set to help keep things stable. (ethereum.org)
Just a heads-up: Goerli is on its way out for application testing. Major providers will be shutting down RPCs around March to April 2024, so it's time to find a new testing ground. (alchemy.com)
Mark your calendars because Holesky will be deprecated as of September 1, 2025. The new go-to for validator and staking testing is Hoodi. Developers should definitely focus on Sepolia moving forward. (blog.ethereum.org)
L2s are now all about Sepolia. You'll see OP Sepolia, Arbitrum Sepolia, and Base Sepolia popping up everywhere. So, make sure to plan your bridge and fee tests accordingly! (docs.optimism.io)
Lastly, keep an eye on the Dencun (EIP-4844) activation timeline for testnets in 2024: Goerli will activate on January 17, Sepolia on January 30, and Holesky on February 7. The mainnet is set to follow in March 2024. (blog.ethereum.org)

Final word: make testnets a competitive advantage

Enterprise programs often fall behind schedule, not due to the complexities of Solidity, but because their pre-production environments are quite delicate. The move to Sepolia and Sepolia-based Layer 2 solutions opens up some exciting possibilities: clearer cost signals following Dencun, more reasonable faucets, improved account abstraction and zero-knowledge parity, plus a more straightforward compliance narrative.

7Block Labs offers a neat package that includes everything you need: vendor selection that's SOC2-aware, reliable test stacks, plus end-to-end contracts along with ZK and AA delivery, all linked to your business KPIs.

Bold, measurable outcomes:

Quicker release trains with a lot less downtime thanks to fewer faucet-induced failures
Spot-on gas forecasts even in a blob-fee environment
Streamlined security and procurement cycles with SOC2-ready infrastructure
Reduced last-minute surprises on bridges, AA, and ZK verifiers

Schedule Your 90-Day Pilot Strategy Call

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References

EF: Holesky is shutting down, so make sure to use Sepolia for your apps and Hoodi for your validators. Check out the full scoop here.
Ethereum.org: For app development, Sepolia is now the go-to network, and Hoodi's your pick for validating and staking. Also, keep an eye out for L2 testnets with the “-sepolia” tag. More details can be found here.
Goerli Deprecation: Important dates are coming up! Goerli will be phased out on April 1, 2024, for Ethereum, and even sooner for L2s. Get the full rundown here.
EIP-4844 (Dencun): Mark your calendars for the testnet dates and blob context. Mainnet is expected to follow in March 2024. Get all the details here.
Post-Dencun Fees: After Dencun, expect transaction fees on L2s to drop significantly--by 90% to 98%! Read more about it here.
Chain IDs and Explorers: If you're looking for Chain IDs, Sepolia is 11155111. You can find more info on Hoodi here.
Faucets: For Sepolia, check out the Google Cloud faucet, and get some guidance on Chainstack faucets here.
AA Entrypoint Addresses: If you need reference values for AA entrypoints on Sepolia, you can find them here.
Tenderly Virtual TestNets: Explore dependable environments with Tenderly’s Virtual TestNets here.
SOC2 Positioning: Chainstack is rocking a Type II SOC2 certification, and QuickNode also has SOC2 status. Check it out here.

Book a 90-Day Pilot Strategy Call

Ready to dive in? Let’s get started! Schedule your 90-Day Pilot Strategy Call today. It’s the perfect opportunity for us to chat about your goals and create a game plan together. Just click the link below to secure your spot.