---
id: "2021-06-29-github-copilot-codex"
url: "https://postcutoff.com/e/2021-06-29-github-copilot-codex/"
as_of: "2026-11-13T13:49:00+01:00"
date: "2021-06-29"
date_precision: day
category: product
importance: 4
confidence: high
status: [Confirmed]
sources: 3
editor: human editor
human_review: null
version: "2026-10-04"
---

As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/e/2021-06-29-github-copilot-codex/

# GitHub Copilot and OpenAI Codex bring LLMs to programming

GitHub launched Copilot as a technical preview, an AI pair programmer powered by OpenAI Codex, a GPT model fine-tuned on public code; the Codex paper introduced the HumanEval benchmark.

## Key facts
- Copilot technical preview announced 29 June 2021
- Codex paper 'Evaluating Large Language Models Trained on Code', arXiv 2107.03374 (July 2021)
- Introduced HumanEval (164 hand-written Python problems)
- Copilot became generally available in June 2022

## What happened

Copilot offered inline code completions in editors, generating whole functions from comments and context.

## Why it matters

The first mass-market generative AI product for professionals; coding became the flagship LLM use case, leading to coding agents like Claude Code.

## Your AI and this story

- GPT-6 Astra (training cutoff April 2026): in its training data
- Claude Opus 5.5 (training cutoff June 2026): in its training data
- Gemini 4 Hydrogen (training cutoff March 2026): in its training data
- Grok 4.7 (training cutoff May 2026): in its training data

## Sources

1. [Evaluating Large Language Models Trained on Code (arXiv)](https://arxiv.org/abs/2107.03374) (arxiv.org, paper)
2. [Introducing GitHub Copilot: your AI pair programmer (GitHub Blog)](https://github.blog/news-insights/product-news/introducing-github-copilot-ai-pair-programmer/) (github.blog, official)
3. [Wikipedia: GitHub Copilot](https://en.wikipedia.org/wiki/GitHub_Copilot) (en.wikipedia.org, discussion)

## Changes

- 2026-09-29 (filed): Created

## Related

- 2025-02-24: [Claude 3.7 Sonnet (hybrid reasoning) and Claude Code preview](https://postcutoff.com/e/2025-02-24-claude-3-7-sonnet-claude-code/index.md)
- 2020-05-28: [GPT-3 (175B) shows in-context few-shot learning](https://postcutoff.com/e/2020-05-28-gpt-3/index.md)