Cursor
In plain wordsA code editor built around AI, in which programmers can ask a model to write, change or explain code across a whole project, or hand it tasks to finish on its own.
An AI-centered code editor developed by the company Anysphere as a fork of Microsoft's open-source Visual Studio Code, keeping that editor's interface and extensions while integrating language models more deeply. Its features include multi-line, next-edit prediction ('Tab') that anticipates where and what the developer will change next; chat and inline editing grounded in an index of the whole codebase; an agent mode that plans multi-file changes, runs terminal commands and tests, and iterates on errors; background agents that work in cloud environments; and project rules files that give agents standing instructions. Users choose among frontier models from several providers, alongside the company's own models. Cursor became a leading example of an AI-native development environment, closely associated with the rise of vibe codingvibe coding, n.: Programming by conversation: you ask an AI for what you want, try out what it produces and ask again until it works, trusting the code without really reading it. and coding agentscoding agent, n.: An AI agent that writes and fixes software by itself: it reads a codebase, edits files, runs commands and tests, and keeps working until a feature is built or a bug is fixed., and a commercial rival to GitHub CopilotGitHub Copilot, prop. n.: An AI assistant from GitHub, built into programmers' code editors, that suggests code as they type, answers questions about code and can carry out coding tasks on its own..
I asked Cursor's agent to migrate the tests to the new API, then reviewed its diff file by file.
Origin
Anysphere was founded in 2022 by four Massachusetts Institute of Technology students — Michael Truell, Sualeh Asif, Arvid Lunnemark and Aman Sanger — who released Cursor in 2023. It grew rapidly in 2024–2025, training its own models for Tab completion and, in October 2025, releasing Composer, an in-house agentic coding model. SpaceX, which had absorbed xAIxAI, prop. n.: An artificial intelligence company founded by Elon Musk in 2023 that makes the Grok chatbot. It is now part of Musk's rocket company, SpaceX., agreed in June 2026 to buy Anysphere in an all-stock deal valuing it at about US$60 billion, and completed the purchase in August 2026.
Usage note
Its rules files are an instance of the agent instruction fileagent instruction file, n.: A plain-text file kept in a software project that tells AI coding agents how the project works — how to build and test it, which conventions to follow, what to avoid — read at the start of every session. convention. Not to be confused with the on-screen text cursor or with database cursors.
Related
- GitHub CopilotGitHub Copilot, prop. n.: An AI assistant from GitHub, built into programmers' code editors, that suggests code as they type, answers questions about code and can carry out coding tasks on its own.
- coding agentcoding agent, n.: An AI agent that writes and fixes software by itself: it reads a codebase, edits files, runs commands and tests, and keeps working until a feature is built or a bug is fixed.
- vibe codingvibe coding, n.: Programming by conversation: you ask an AI for what you want, try out what it produces and ask again until it works, trusting the code without really reading it.
- Claude CodeClaude Code, prop. n.: A coding assistant from Anthropic that works as an agent: given a programming task, it explores the project, changes the code and runs programs to check its work, from the web, a desktop app, an editor or a terminal.
- agent instruction fileagent instruction file, n.: A plain-text file kept in a software project that tells AI coding agents how the project works — how to build and test it, which conventions to follow, what to avoid — read at the start of every session.
- code generationcode generation, n.: Having an AI write computer code from a description in plain language, from finishing a single line as you type to building whole programs.
Mentioned in
GitHub CopilotGitHub Copilot, prop. n.: An AI assistant from GitHub, built into programmers' code editors, that suggests code as they type, answers questions about code and can carry out coding tasks on its own., AI coding assistantAI coding assistant, n.: AI software that helps people write computer programs — suggesting the next lines, explaining code, finding bugs or making changes on request — inside the tools programmers already use.