An Open Letter from the Bella Engineering Team

Dear Bella community,

Today, we announce with joy that the wait for Flex Savings v2 (Mainnet release plus improvements) is finally coming to an end. We are working diligently to prepare for the initial public release.

Going back to the stubborn decision we made ~2 months ago: instead of releasing Flex Savings, risk it, and ride the tides, we slowed down and concentrated on improving the overall quality of the product. And these ~2 months took us on a journey that led to many fundamental improvements as well as explorations of engineering best practices in the DeFi space.

What happened behind the scenes?

We have noticed that projects audited by multiple security firms still got really severe problems. The reason is simple, security audits only analyze the soundness of the protocol design. It is an investigation of the blueprint, not a test drive of the prototyped car built from that blueprint. Losing that silver bullet, we then quickly decided to turn to the old school “testing until it breaks” approach to improve the quality.

All engineering practices are similar. If you want to know the quality (durability) of the keyboard you manufactured, what would you do? First, you set it under a machine that automatically strikes it a couple of million times until it breaks. Then, write down the number. Do this repeatedly to more keyboards to find an average.

Finally, you have a steady number saying: “On average, one million strokes will break the keyboard.” Now you can say it with confidence, the durability of my keyboard is one million keystrokes. As you can see, nothing grants more confidence to the quality of a product than smart and thorough testing.

So what we essentially did is that we built a customized “keystroke machine” to keep “striking” Flex Savings until it breaks; discover what broke it, and patch them up.

Specifically, we learned to build a “Time Machine” so we can go back and forth freely on block-time in a simulated Ethereum universe. This made our testing and debugging much easier since we could always rewind to any previous state of the blockchain to figure out at which state a problem might have occurred.

We have also built utilities around the “Time Machine”. These are the reusable tools tailored to our protocol that allows us to quickly implement as many test cases as possible in parallel.

Then, we built a Emulator, which is the infrastructural protocol that Flex Saving depends on. The reason being, in the smart contract world, any protocol is only as safe as its dependency. We went from treating as a black box with an abi to being able to 100% comprehend not only the mathematical models but also how the engineering decisions were made to the logic of every line of the Curve Protocol implementation.

As a result, we have added ~20,000 lines of testing scenarios code, fixed numerous bugs that would have stayed otherwise elusive and undetectable by the audits, refined pricing strategy from understanding implementation details of Curve to maximize users’ returns, as well as integrating to new pools with higher yields.

Finally, we sincerely apologize for the extra time spent and we are super grateful for your patience. At the same time, we hope that our lovely community can understand the reasoning behind this decision just like how many of you who had bought a copy of the prematurely released Cyberpunk 2077 had experienced. We were able to avoid making a similar mistake that even one of the best developer teams around the world had made, with the intention to deliver a higher quality product into your hands.

The engineering team at Bella welcomes anyone to help us improve our product for the community. Please feel free to join our Discord developer channel or reach out to our Tech Lead at Tech Lead#6623 on Discord. We are hiring ;)

About Bella

Bella is a suite of open finance products including automated yield farming tools, lending protocol, 1-click savings account, customized robo-advisor, and more. We believe everyone deserves equal access to premium financial products and services with elegant design and smooth user experience.

Bella brings your familiar mobile banking into crypto with just one click. With Bella, you can just simply sit back, watch your asset grow, and leave all the heavy-lifting to secure, automated smart contracts.

Bella’s core team consists of serial entrepreneurs and blockchain veterans who have tremendous experience and proven track record in finance, cryptography, blockchain, and engineering.

For more information about Bella, or to join our team, please contact us at

Learn about Bella’s recent official news at:


Twitter: @BellaProtocol


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Bella Protocol

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A suite of DeFi products to bring your familiar mobile banking into crypto with just one-click.

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