Cosine

A Colleague, Not a Copilot

Most AI coding tools act as glorified autocomplete — suggesting the next few lines while you do the heavy lifting. Cosine's Genie takes a fundamentally different approach. It's built to reason about code the way a human developer does: reading the full codebase, understanding context and dependencies, and autonomously writing, debugging, and refactoring code from a simple natural language prompt.

Founded in 2022 in London by Alistair Pullen, Yang Li, and Sam Stenner, Cosine emerged from Y Combinator and quickly caught attention by achieving a 30% score on the SWE-Bench benchmark — a standardized test that measures how well AI can autonomously resolve real-world GitHub issues. At the time, that score surpassed competitors including Cognition AI's Devin.

How It Works

Genie ingests your entire codebase and builds a deep semantic understanding of how everything fits together. When given a task — fix this bug, add this feature, refactor this module — it plans its approach, writes the code, tests it, and iterates. The result is production-ready pull requests, not code snippets.

Why It Matters

The $2.5 million seed round, backed by Y Combinator and angel investors, positions Cosine to scale its vision of making every development team more productive. As AI coding tools become table stakes, the companies that can deliver truly autonomous engineering — not just suggestions — will define the next era of software development.

About Alistair Pullen

Alistair Pullen is the CEO and co-founder of Cosine, the London-based AI startup building autonomous coding agents. Along with co-founders Yang Li and Sam Stenner, Pullen launched Cosine in 2022 with the vision of creating AI that reasons about code the way experienced human developers do.

Cosine was accepted into Y Combinator and quickly made waves in the AI coding space. The team built Genie, which achieved a 30% score on the SWE-Bench benchmark — outperforming well-funded competitors at the time. Pullen's approach emphasizes deep codebase understanding over surface-level code completion.

Under Pullen's leadership, Cosine raised a $2.5 million seed round and has focused on building AI that can serve as a genuine engineering colleague rather than another autocomplete tool. The company continues to push the boundaries of what autonomous AI agents can accomplish in software development.

Co-Founders

Accelerator

30%

SWE-Bench Score

2022

Year Founded

Sources: Public press releases, SEC and state business filings, published interviews, news coverage, and company disclosures.

A Colleague, Not a Copilot

How It Works

Why It Matters

About Alistair Pullen

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