We've encountered cases where a client's arbitrage bot lost up to 30% of its profit (approx. $15,000/month) due to front-running: public transactions were intercepted by MEV bots that set higher gas and grabbed liquidity. After implementing a private mempool for private Ethereum transactions based on a Flashbots relay, losses dropped to 2-5%, saving about $10,000/month, and the setup paid for itself in one month. The main cause of losses is the transparency of the public mempool: any unconfirmed transaction is visible to all network nodes. MEV bots analyze it and insert their own transactions before yours, capturing the profit.
Over five years, we have delivered more than 30 projects for transaction protection on Ethereum, Polygon, BNB Chain, and other EVM networks. Our experience shows that a properly configured private mempool can reduce MEV-related losses by up to 90%.
Why a Private Mempool Protects Better Against MEV
A private mempool sends the transaction directly to a block builder, bypassing the public broadcast. The builder includes it in a block without prior disclosure. This blocks the three main MEV attacks:
- Sandwich attack: the bot cannot see your transaction and thus cannot insert a buy before and a sell after.
- Liquidation front-running: the liquidator cannot intercept your position on Aave/Compound.
- Arbitrage pre-emption: arbitrageurs cannot react to your trades within the block.
This provides front-running prevention and sandwich attack protection.
Comparison of Private Submission Solutions
| Solution | Type | Front-running Protection | Inclusion Cost | Setup Complexity |
|---|---|---|---|---|
| Flashbots Protect RPC | Public relay (free) | Yes | 0 Gwei | Low |
| Flashbots Bundle API | Relay for bundles | Yes, atomic | Coinbase payment (tip) | Medium |
| MEV Blocker | Aggregator of searchers | Yes | 0 for sender | Low |
| bloXroute | Enterprise relay | Yes | Subscription | High |
| Custom relay (MEV-Boost setup) | Infrastructure project | Full | Only gas | Very high |
Flashbots Protect is 10 times faster than the public mempool in inclusion time—on average, a transaction lands in the next block. Additionally, gas savings from bundle optimization reach 20%, and average monthly savings from MEV reduction are $5,000–$10,000.
How to Configure a Private Mempool in 5 Steps
- Choose a Flashbots relay. For a quick start, use Flashbots Protect RPC. Change the endpoint in your code or wallet.
- Integrate via ethers.js. Connect the provider to
https://rpc.flashbots.net. All transactions now go through the private Ethereum RPC channel. - For bundle submission, form a bundle (for complex operations). Assemble a sequence of transactions, sign them with
@flashbots/ethers-provider-bundle, and submit with a target block number. - Set up coinbase payment. Include an ETH transfer to the builder's address in the bundle; the tip size determines priority. This is an anti-MEV measure. Typical fee is 1-5% of the operation's profit.
- Submit in parallel to multiple relays to increase inclusion reliability.
- Monitor inclusion rate. Track the percentage of successful inclusions within the target block ± 2.
Key Metrics to Track After Setup
After implementation, we typically see the following improvements:
- Inclusion rate increases from 70-80% to 95%+.
- MEV savings — loss reduction of 80-90% (typical monthly savings of $5,000–$20,000).
- Gas efficiency — bundles use 15-25% less gas due to order optimization.
- ROI on setup is 2-3 months for projects with transaction volumes above $50k/day.
Deliverables: What You Get
We handle private RPC setup for your dApp or bot — turnkey. Our package includes:
- Analysis of your transaction flow and selection of the optimal relay (Flashbots, MEV Blocker, or a custom relay).
- Integration of SDKs (ethers.js, viem, web3.py) with code documentation and examples.
- Configuration of MEV-Boost on your validator (if you run your own staking).
- Optimization of gas parameters and coinbase payment for maximum inclusion rate.
- Deployment of Grafana monitoring with metrics for losses and savings.
- Training for your team: a workshop on bundle and nonce management.
- SLA: incident response time of 2 hours during business hours.
We will evaluate your project for free — contact us via Telegram or email. To order a private mempool configuration, get in touch for a consultation.
Why Order the Setup from Us?
We have been working with blockchain for over five years, delivering more than 30 solutions for MEV protection for DeFi protocols and arbitrage bots. Our engineers are authors of open-source transaction protection tools. We guarantee gas savings of up to 20% thanks to bundle optimization.