Effect: from a fintech sandbox to production TypeScript
Effect is an open-source TypeScript library for building production-grade software. It was incubated and funded at Creditscript, the fintech I founded, and I sit on the board of Effectful Technologies, the company behind it. This page sets out the record.
Timeline
- 2015
- I found Creditscript, a fintech building a real-time marketplace for trading loans, and develop it in stealth.
- 2018
- Creditscript comes out of stealth and launches in London. Its engineering team, led by CTO Michael Arnaldi, builds a functional effect system for TypeScript to meet the consistency and audit requirements of a regulated lending platform. It becomes the foundation of Effect, developed inside the FCA Regulatory Sandbox, building on the work of fp-ts.
- 2020
- Creditscript adds compile-time execution tracing to the framework through TypeScript compiler plugins.
- 2023
- I join Effectful Technologies, the company behind Effect, as a Non-Executive Director. Effectful is backed by Amplify Partners.
- February 2024
- The first Effect Days conference takes place in Vienna, with more than 120 attendees, 13 talks and two workshops. (Effect, Wrapping up 2024)
- April 2024
- Effectful, the company behind Effect, founded by Michael Arnaldi, raises a $2.275 million seed round led by Amplify Partners, with participation from early adopters. (Effect 3.0 release notes; Amplify Partners, Our Investment in Effectful, 16 April 2024)
- April 2024
- Effect 3.0 is released, and the core package is declared stable after five years of work. (This Week in Effect, 19 April 2024)
- June 2024
- Effect wins the "Most Exciting Use of Technology" award at JSNation in Amsterdam. (Effect, Wrapping up 2024)
- 2025
- The second Effect Days, extended to three days, takes place in Livorno, Italy. Over the year Effect adds an AI SDK for agent-based systems and an alpha of durable workflows. (Reflections on Effect Days 2025; Effect 2025 year in review)
- September 2026
- Effect 4.0 is released: rebuilt from the ground up, with a core that has no runtime dependencies and a long-term support commitment to at least September 2029. Effect reports about 43.9 million weekly npm downloads in the week of 21 September 2026, 179 times the level when version 3 was released. (Effect 4.0 release notes)
Talks and interviews about Effect are collected on the Videos page.