GitHub Copilot Launches — The Day an AI Pair Programmer Moved Into the Editor

On 29 June 2021, GitHub released GitHub Copilot—an AI code-completion product built jointly with OpenAI—as a technical preview. It sat in the sidebar of VS Code and could write entire function bodies from a comment or a signature. For the first time, mainstream developers were handing the wheel of their editor to an AI.

On 21 June 2022 it became generally available as a US$10/month personal subscription. Within a few years the industry's development experience had been rebuilt in a way that could no longer be undone.

Codex Under the Hood

Behind Copilot ran OpenAI's Codex model—GPT-3 fine-tuned on public code from GitHub, fluent across dozens of languages. At the time, Codex was the clear winner in the narrow but valuable task of "predict the next 3–30 lines of code".

IntelliSense and TabNine had offered completion before, but no shipping product had been willing to write whole functions in one shot. Copilot was the first mass-market product to cross that line.

Doe v. GitHub — Collision with Open Source

On 3 November 2022 a group of anonymous developers filed a class action in the Northern District of California against GitHub, Microsoft, and OpenAI. Counsel: Matthew Butterick with the Joseph Saveri Law Firm. Two core claims.

1. Open-source licence breach. MIT, GPL, and Apache-licensed code on GitHub had been used as training data and was being regenerated by Copilot without attribution or licence inheritance—a breach of the licence contracts.

2. DMCA §1202 violation. Stripping Copyright Management Information (CMI)—author names, licence notices—from outputs is itself unlawful.

In May 2023 the direct copyright-infringement claims were dismissed for lack of specific examples of copied code. In July 2024 the DMCA claims were also dismissed, leaving only contract-style claims (licence breach, unfair competition) standing. No court has ruled that Copilot is unlawful, but the case became the first formal challenge to the unspoken premise that "public code = free training material".

The Copilot suit was the precursor to New York Times v. OpenAI (2023) and the wave of suits against generative-image models.

Productivity — Belief and Doubt

A 2022 controlled experiment by GitHub had developers implement an HTTP server in JavaScript. The Copilot group finished 55.8% faster than the control (n=95, p=.0017). A separate measure: roughly 30% of suggestions were accepted as-is. A larger 4,800-developer joint study with Accenture later reported statistically significant productivity gains as well.

But in July 2025 the non-profit research lab METR published a randomised controlled trial pointing the other way. Experienced open-source developers, working on real tasks, felt 20% faster with AI tools—but measured 19% slower. The gulf between perceived and actual speedup showed that tool choice and workflow design mattered far more than the marketing suggested.

The anxiety that "junior developers will be wiped out" runs in parallel. If completion can fill in more and more code, the rungs on which a beginner climbs to expertise get sawed off. From 2024 onward that worry has fused with a cooling hiring market into an unspoken industry-wide unease.

Cursor, Windsurf, Claude Code — The Insurgents Catch Up

2024 was the year AI coding IDEs exploded. Anysphere's Cursor forked VS Code, added multi-file editing and the "Composer" agent, and grew so fast it hit US$1 billion ARR in under two years—the fastest SaaS ever, by many measures. Codeium rebranded to Windsurf. Sourcegraph Cody discontinued its Free and Pro tiers in July 2025 to focus on enterprise. Anthropic released Claude Code in February 2025 and reached $1 billion ARR six months later.

GitHub went on the defensive. In December 2024 it shipped Copilot Free (2,000 completions/month). In early 2025 it cut the personal plan from US$19 to US$10 and rebranded it "Pro". It also rolled out Copilot Workspace (spec → implementation → PR end-to-end) and Copilot Agents (autonomous task execution). Pricing settled at Pro US$10, Business US$19, Enterprise US$39 per seat per month.

A Whole Industry Pivots

Five years after Copilot's preview, nearly every part of the software industry has bet on AI dev tools. The 2025 Stack Overflow Developer Survey: 84% of developers use or plan to use AI tools; 51% of professionals use them daily; only 29% trust their output. "I use it but I don't believe it" is the honest median.

Copilot will be remembered less as a single product than as the product that rewrote the industry's defaults. Having an AI live inside the editor became normal, and the ripples it set off across licensing, productivity, and the labour market are still moving.