Proposer-Builder Separation
Before PBS, validators both built and proposed blocks — giving them direct MEV extraction power and creating centralization pressure. PBS separates these roles: specialized builders compete to assemble the most valuable block, and validators simply pick the highest bid.
MEV-Boost Block Flow
Watch how a block moves from builders through relays to the proposer. Click animate to see the bid auction in action.
Block Building Simulator
Winning Bid
—
Proposer Revenue
—
Builder Margin
—
Builder Market Share
Approximate market share based on recent Ethereum blocks. Concentration is a key censorship risk.
Relay Trust Model
Trusted Relays (Current)
- Relay sees full block contents
- Must be trusted not to steal MEV
- Can censor transactions
- Examples: Flashbots, bloXroute, Ultrasound
Optimistic Relaying
- Relay forwards block header first
- Body revealed after proposer commits
- Reduces latency by ~100ms
- Builder penalized if block is invalid
ePBS (Enshrined)
- No trusted relays needed
- PBS is a protocol-level mechanism
- Inclusion lists for censorship resistance
- Part of Ethereum's long-term roadmap
MEV-Boost vs ePBS
| Feature | MEV-Boost | ePBS |
|---|---|---|
| Trust model | Trusted relays | Trustless |
| Implementation | Out-of-protocol | In-protocol |
| Censorship resistance | Relay-dependent | Inclusion lists |
| Latency | ~200ms relay overhead | Protocol-native |
| Status | Live since 2022 | Research / EIPs |
PBS Stats Dashboard
Blocks via MEV-Boost
~92%
Avg MEV per Block
~0.05 ETH
Top-2 Builder Share
~58%
Active Relays
8