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Case Study

How Coherent saved two years of development time with GitStart

With only two senior engineers on their team, Coherent had to quickly take their solution to the market. GitStart helped them rebuild Excel functions that compute up to 330 times faster, saving two years of development time.

AndreeaAndreeaApril 16, 2024

Meet Coherent

Coherent is a New York-based software-as-a-service company that revolutionizes insurance companies by converting Excel spreadsheets into APIs, enabling non-developers to handle complex computations.

Its core product can support real-time financial computations and speed up product modeling, with Coherent serving some of the world’s largest insurance companies and financial institutions, including AXA, Prudential, FWD Insurance, and Franklin Templeton Investments.


Unlocking billions of revenue potential with Excel computations

Insurance giants and financial institutions have trillions of cells to compute in Excel files, and any delay in processing leads to further delays in structuring financial products, leading to staggering figures in potential revenue loss.

Coherent’s goal was to quickly deploy their Excel engine to significantly reduce this computation time, potentially unlocking billions in revenue for the industry.

However, with only two senior engineers on the team and over 200 Excel functions to integrate, Coherent needed to find a way to accelerate the project’s go-to-market timeline.


Collaborate with GitStart to rebuild Excel functions that compute so much faster

Coherent laid out the architecture, and GitStart led the execution in C++.

By assigning well-scoped tickets in JIRA to GitStart and specifying clear performance benchmarks, GitStart could ship over 500 pull requests that led to significant performance improvements.

We improved more than 200 functions in Excel to work better and faster, helping Excel tasks run smoother. The work involved deep research into mathematics textbooks, actuarial books, and financial sites to find algorithms and explanations for how to optimize the functions, with little to no resources available. Oftentimes, the only option was to build the function from scratch.

Some of the major improvements we’ve made are as follows:

  • Faster spreadsheets with dependency mapping: We created a system that studies Excel formulas and constructs dependency graphs to figure out the fastest way to process them.

  • Formula Pre-calculation. We made Excel formulas calculate earlier so they don’t need to use dynamic inputs while they’re loading, making things run much faster.

  • Thorough Testing. We set up comprehensive regression and unit testing verified through GitHub actions, making sure every piece we add passes each test, so we can keep the quality high and reduce any risks.


330-fold improvement in computational time

Out of over 200 Excel functions, specific functions registered a notable decrease in computation time, up to 330 times faster.

10x more development capacity with GitStart

With only two senior engineers on the Coherent team helping us scope tasks and review code, we managed to release to market at least two years ahead of the original roadmap.


GitStart supported Coherent in maintaining a competitive edge, unlocking millions of downstream revenue for Coherent’s clients and other stakeholders.

With only two senior architects and a quality assurance engineer, working with GitStart allowed Coherent to dramatically accelerate the project’s go-to-market timeline, saving two years of development time.

Last but not least, GitStart’s innovative pricing model based on merged pull requests proved to be a cost-effective solution that aligned with Coherent’s need for scalability and quality at speed.