Tangelo: Final Testnet Upgrade Before Mainnet
Today, we are introducing Tangelo, the final Citrea testnet fork before mainnet launch. This upgrade includes our final set of testnet improvements as we prepare for mainnet.
The Tangelo upgrade incorporates all audit fixes and introduces improvements to our fee mechanism. In short, Citrea testnet is now cheaper and more robust!
Implementing Audit Fixes
Citrea recently fully completed its audit phase for both the rollup infrastructure and its BitVM-based bridge, Clementine. The Citrea team successfully resolved all high and medium severity findings, along with other significant issues. The Tangelo upgrade includes all our audit fixes as well as fixes from the BitVM audit itself, bringing major improvements to system reliability, security, and efficiency.
Summary of the fixes:
- Sequencer improvements: Enhanced UTXO selection and transaction handling to ensure consistent behavior under all network conditions and prevent potential edge-case inconsistencies.
- System resilience: Introduced timeout safeguards and refined retry logic to prevent blocking or stalls during external calls and reorg handling.
- Stability and recovery: Fixed issues that could interrupt block production or finalization during restarts, ensuring the sequencer operates reliably across all scenarios.
- Prover enhancements: Improved resource management and parallel proving flow, preventing potential memory issues and optimizing proof generation.
- Bridge reliability: Resolved rare edge cases in Clementine’s state machine and improved fee-bumping logic to ensure smooth BTC withdrawals during fee spikes.
Together, these fixes make Tangelo one of the most stable and secure Citrea releases to date, bringing us closer to mainnet readiness.
Optimizing Fees for Better User Experience
The Citrea team conducted a thorough analysis on our fee mechanism to ensure that Citrea provides competitive fees while inheriting Bitcoin security. The analysis led to optimizations in both base fees and Layer 1 fees.
Citrea transactions consist of two fees: L2 execution fee and L1 fee (inheriting Bitcoin security). Base fees, part of L2 execution fees, represent the cost of executing transactions on Citrea while Layer 1 fees are the estimated cost to publish the transactions on Bitcoin. With the Tangelo upgrade, both have been significantly reduced.
Summary of the changes:
- Base fees reduced by 90%: The minimum base fee has been lowered from 0.01 gwei to 0.001 gwei, making transactions more accessible and aligned with our goal of scaling Bitcoin for every use case.
- Layer 1 fees reduced by 25%: Fee parameters were refined to better match user needs while maintaining full Bitcoin security guarantees.
These changes make Citrea transactions significantly more affordable and better aligned with user needs. The Citrea team continues to explore further optimizations for even more efficient fees in the future.
Tangelo Upgrade is Now Live!
The maintainers successfully upgraded Citrea testnet to Tangelo on November 4th, 2025, at 3:00 PM UTC, at block 17733000. This marks the final Citrea testnet fork, integrating all critical audit fixes and fee improvements.
With the Tangelo now live, Citrea’s infrastructure is in its strongest state yet as we move toward mainnet, enabling builders to deploy the first wave of ₿apps secured by Bitcoin.
Stay Connected
Follow along as we move into the next phase of our road to mainnet: