"100% of my code is written by AI" is a common brag on X. JetBrains decided to measure what's actually happening, and the numbers show a big shift in one year. The data comes from its Developer Ecosystem and AI Pulse surveys, published by JetBrains Research this month and in August.
What developers will hand to AI
Share of developers ready to delegate each task to AI:
| Task | Apr–Jun 2025 | May–Jul 2026 |
|---|---|---|
| Writing application logic | 18% | 50% |
| Writing tests | 50% | 75% |
| Refactoring | 38% | 60% |
| Code review (fully) | 33% | 43% |
Debugging is the clearest holdout: 54% are not ready to delegate it, though that's down from 76% a year ago. JetBrains expects this to shift "as agentic debugging improves".
How much code agents actually write
In May–July 2026, JetBrains asked 15,000+ professional developers what share of last month's work code was agent-written, AI-assisted or fully manual. On average:
- ~47% fully written by agents
- ~38% written with some AI assistance
- ~27% written fully by hand
(Those averages add up to more than 100% because people answered in ranges.)
Other findings:
- Over half write less than 20% of their code manually, and one in five writes none without AI help.
- Only about 22% rely almost entirely on agents (over 80% agent-generated).
- Seniors lead: about a quarter of senior developers generate over 80% of their code with agents, more than juniors.
- By tool: 32% of developers whose main tool is Claude Code generate over 80% of their code with agents, versus 42% for Codex users. JetBrains puts Claude Code's adoption at work at 39%.
- By language: Go, JavaScript and TypeScript are the most agentic (54–55% agent-generated on average). C and C++ are the least.
- By region: 32–35% of developers in China, Japan and South Korea generate over 80% with agents, versus about 16% in Europe and the UK.
How developers feel about it
- 79% believe employers will expect AI-tool proficiency, up from 59% in mid-2024.
- 37% think AI coding will reduce demand for professional developers, up from 28% in 2024.
- Nearly a quarter think AI will eventually replace human developers entirely, up from 8% in 2024. Among heavy agent users the figure is 37%.
What to take from it as a builder
- The gap is review. Developers happily hand over writing and tests but not reviewing or debugging. JetBrains itself recently wrote that "the bottleneck is no longer code generation; it's review." Get good at it with our guide to reviewing AI-written code and the code review skill.
- Tests are the easiest win. Three-quarters of developers already delegate them. If your agent isn't writing tests, start there.
- Context makes delegation work. Handing more work to an agent goes better when it knows your project's rules. An AGENTS.md is the cheapest upgrade.
- Pick a tool, then learn it deeply. See Cursor vs Claude Code vs Codex and our Codex CLI guide.
About the data
JetBrains says the survey is localized into eight languages, uses regional quotas, and is reweighted to represent the global developer population. About 90% of respondents are developers, programmers or software engineers. The tool-level comparisons come from respondents' own reports of their most-used tool. They describe who uses each tool, not how good the tools are.
