Best MEV Relays by Chain (2026 Direct Execution Guide)

Answer first — MEV relay landscape in 2026 is fundamentally per-chain. Ethereum mainnet runs on a multi-builder fan-out model: serious searchers submit eth_sendBundle simultaneously to Flashbots, Titan, beaverbuild, and rsync-builder, with bloXroute as a paid commercial option. Solana is dominated by Jito Block Engine — bundles tip Jito tip accounts and are routed to participating validators; this is the only reliable way to get atomic inclusion on Solana. BNB Chain has Puissant (BSC-aligned validator path) and bloXroute BSC for the lowest-latency mempool subscription. Polygon has FastLane Atlas, a PBS-style auction running on the validator set with partial coverage; pair with public-mempool fallback. Optimism / Base / Arbitrum have no Flashbots-style bundle relays — atomicity comes from packing into a single executor-contract call. Match the relay to the chain; do not run "Ethereum-style" relay assumptions on chains that don't support them.

Mastery path

• What is MEV?
• Best Ethereum private RPCs
• Flashbots bundles explained
• Best MEV relays by chain (current)
• Jito bundles explained

Ethereum mainnet: multi-builder fan-out

Single-relay submission is a 30–60% block-share blind spot in 2026. The modern default is fan-out:

Fan-out same bundle to all four base relays simultaneously; first inclusion wins. Track per-relay inclusion rate and re-weight your fan-out toward consistent winners. The FRB Agent does this automatically.

MEV-Share is a separate hint protocol (not a builder); use it when you want OFA refund flow, but it doesn't replace eth_sendBundle to builders.

Solana: Jito Block Engine

Solana doesn't have a public mempool; transactions are forwarded directly to validators. Jito Labs runs a block engine that lets searchers submit atomic bundles to Jito-aware validators:

• Submission: bundle of (your tx + a Jito tip tx going to one of Jito's tip accounts).
• Tip dynamics: Jito sorts bundles by tip per compute unit. Static tip values lose; adaptive tipping calibrated against current slot leader's recent winning-tip distribution wins.
• Coverage: Jito-aware validators currently process the majority of stake on the Jito-MEV path. Non-Jito slot leaders ignore your bundle entirely — your tip falls into a different submission path.
• Failure mode: wrong slot leader (not Jito-aware), tip too low to clear, bundle malformed.

For Solana strategies (Pump.fun sniping, Raydium backruns, Jupiter-routed arbitrage) Jito is the canonical relay. There's no real alternative for atomic execution; non-Jito sends are first-confirmation roulette.

BNB Chain: Puissant + bloXroute

BSC has a real public mempool but no Flashbots-equivalent in the original sense. The relay landscape:

• Puissant — BSC-aligned validator path with direct relay access. Effective during normal hours; coverage depends on which BSC validators are integrated.
• bloXroute BSC — paid commercial relay with high-quality global infrastructure. The lowest-latency mempool subscription available for serious BSC operators.

Operating BSC strategies typically dual-routes bundles to both Puissant and bloXroute (where economics justify the bloXroute fee) to maximise inclusion across the validator set. The validators historically had an informal anti-MEV understanding that's been weakening; assume the validator set will sort by economics, not by neutrality.

Polygon: FastLane Atlas

Polygon's Heimdall + Bor architecture didn't have a Flashbots equivalent until FastLane Labs built FastLane Atlas, a PBS-style auction running on the Polygon validator set:

• Submission: atomic bundle through FastLane endpoints.
• Coverage: participating validators only. Non-participating slot leaders can't include your bundle.
• Pair with fallback: public-mempool fallback (with strict caps) for slots where the proposer isn't FastLane-aware.

For serious Polygon MEV in 2026, FastLane is the right tool when economics permit. For lower-volume operators, public-mempool with very strict slippage and gas caps still works — Polygon doesn't have the contestation level of mainnet.

Optimism, Base, Arbitrum: no bundle relay

These chains do not have Flashbots-style bundle relays. The closest substitutes:

• Single-tx atomicity through an executor contract. Pack your route into one transaction that calls a contract; the contract reverts on partial fill. The whole thing either lands or doesn't.
• Private RPC endpoints that don't rebroadcast your tx to the public peer-to-peer layer until inclusion. Most commercial RPCs sell this as a paid feature.
• Direct sequencer submission (allowlist) for very latency-sensitive flows on Arbitrum. Limited availability.
• Timeboost on Arbitrum — auction-priced express lane for sub-block priority.

The mistake to avoid: assuming "private bundle" semantics from Ethereum work the same way on these chains. They don't, and configuring your bot as if they do is a slow gas leak.

Choosing the right configuration

The FRB Agent ships with chain-appropriate relay configurations enabled per chain by default.

Relay Health Monitoring and Rotation Protocol

Setting up the correct relay configuration is step one. Monitoring relay health and knowing when to rotate is what separates stable operations from ones that mysteriously stop working mid-session.

Signs a relay is degraded:

• Inclusion rate drops 20%+ from your baseline for the same strategy without any fee model change
• P95 round-trip time to the relay increases above 150ms on Ethereum or 80ms on Solana
• You receive explicit error codes: builder_rejected, relay_timeout, or bundle_simulation_failed at above 5% rate
• Relay dashboard (if available) shows reduced builder participation

Rotation procedure:

1. Log the degradation event with timestamp and relay name before any action
2. Switch fan-out weight away from the degraded relay (reduce to 0% if error rate is high)
3. Verify standby relay is pre-warmed (send a lightweight test bundle)
4. Resume with standby relay carrying the full allocation
5. Monitor inclusion rate over the next 50 bundles to confirm recovery

Weekly relay audit: Even during periods with no visible degradation, run a 30-minute relay audit weekly. Compare per-relay inclusion attribution (FRB logs this per relay) and re-weight toward highest-performing paths. Builder market share shifts month-by-month; what was optimal in Q1 may not be optimal in Q3.

References

• Flashbots eth_sendBundle reference
• Jito Block Engine docs
• FastLane Atlas
• bloXroute BDN
• Inclusion Probability 101
• Fixing Failed Bundles Guide