Claude Code falls from the top. Codex becomes No. 1 in market share. ～Summary of AI Coding trends in March 2026 based on data～
AI Coding Agent trends in March 2026
We have been operating a site called AI Coding.Info since July 2025.
This is a site that observes usage trends related to AI Coding Agents such as Claude Code, Codex CLI, Github Copilot, and Gemini from a fixed point from information in Github repositories. To determine the use of AI Coding Agent, we conduct daily surveys under the following conditions.
- Daily inspection of 9,000 public repositories on Github
- TOP 300 Github stars by programming language
- Researched from 30 types of programming languages
- Targets 16 types of AI Coding Agents
- Only when the rule files used by various AI Coding Agents are in the Github repository, it is determined that AI Coding Agent is being used.
Last month's trends
https://qiita.com/kotauchisunsun/items/8ff87803193ff448f4eb
AI Coding Agent usage rate is 8.7%
AI Coding Agent repository utilization rate is 8.7%, an increase of 1.4% from 7.3% last time. This is growing at a fairly fast rate. Again, we estimated the overall growth rate to be approximately 0.73% [as of November 2025] (https://qiita.com/kotauchisunsun/items/7b32a5f969a6322d66b4). In December 2025, the penetration rate will be 7.29 to 8.01% at the end of 2026. The prediction was issued. The fact that it is 8.7% as of April 1, 2026 means that abnormal growth is occurring. **
AI Coding Agent usage rate on April 1, 2026
https://ai-coding.info/ja?since=2026-03-01&until=2026-04-01&date=2026-04-01#adoption-rate
AI Coding Agent usage rate on March 1, 2026
https://ai-coding.info/ja?since=2026-03-01&until=2026-04-01&date=2026-03-01#adoption-rate
Changes in the number of repositories using AI Coding Agent from 2026/3/1 to 2026/4/1
https://ai-coding.info/ja?since=2026-03-01&until=2026-04-01&date=2026-03-01#ai-usage-line-chart
Share of AI Coding Agent by product
The share by product is as follows.
| Ranking | Product name | Share rate |
|---|---|---|
| 1st place | Codex CLI | 34.1% |
| 2nd place | Claude Code | 32.4% |
| 3rd place | Copilot Agent | 19.0% |
| 4th place | Cursor | 6.3% |
| 5th place | Gemini CLI | 6.0% |
last month,
Codex CLI continues to gain momentum. I have the impression that it will overtake the number one Claude Code in terms of market share. Until last month, there was a 4% difference between Claude Code and Codex, but this month, the difference is only 0.7%. Therefore, it is only a matter of time before Codex takes over.
As I wrote, that's exactly what happened. **Codex ranked first in market share. ** I feel a little strange because most of the people around me are Claude Code fans and I don't really look at Codex. Regarding the counting method of Codex, it is determined based on the presence or absence of "AGENTS.md", so we cannot deny the possibility that the market share seems larger due to other factors than Codex.
AI Coding Agent share rate on April 1, 2026
https://ai-coding.info/ja?since=2026-03-01&until=2026-04-01&date=2026-04-01#agent-share
AI Coding Agent share rate on 2026/3/1
https://ai-coding.info/ja?since=2026-03-01&until=2026-04-01&date=2026-03-01#agent-share
AI Coding Agent usage status by programming language
The programming language in which AI Coding Agent is used most is "TypeScript," the second is "Rust," the third is "Go," the fourth is "Python," and the fifth is "C#." In February there was a big change in programming language rankings, but this month it wasn't that big. That's the impression. It was a big shock that Python fell to 4th place in March, but until February there was not much difference between Rust, Go, and Python in 2nd to 4th place. However, in March, I think "Rust" has surpassed it by one. That's the impression I get.
AI Coding Agent ranking by programming language on April 1, 2026
https://ai-coding.info/ja?since=2026-03-01&until=2026-04-01&date=2026-04-01#language-agent-rank
AI Coding Agent ranking by programming language on March 1, 2026
https://ai-coding.info/ja?since=2026-03-01&until=2026-04-01&date=2026-03-01#language-agent-rank
Monthly trends in the number of repositories used by AI Coding Agent
As of 2026/03/01, the number of repositories was 1,008, but as of 2026/04/01, the number of repositories is 1,234. This is an increase of 154 cases. Considering the 15% increase in one month, this is a pretty fast increase.
Changes in the number of repositories using AI Coding Agent from 2026/3/1 to 2026/4/1
https://ai-coding.info/ja?since=2026-03-01&until=2026-04-01#time-based-bar-chart
What triggered the acceleration of AI Coding Agent usage rate?
I will draw the plot from 2025/12/01 to 2025/04/01.
Regarding the Go language, I think the usage rate is steadily increasing. On the other hand, as for Rust and C++, although this is a bit arbitrary, I think there is a point where the numbers have increased sharply around February 12th. If you look at the events that happened around here,
GPT-5.3-Codex-Spark was released on 2/12.
https://developers.openai.com/codex/changelog#codex-2026-02-12-mdx
GPT-5.4 was released on March 5th.
https://developers.openai.com/codex/changelog#codex-2026-03-05-mdx
That explains why, to some extent, the release of GPT-5.3-Codex-Spark and GPT-5.4 has increased the usage rate of AI Coding Agents for Rust and C++. And there is a hypothesis that ``the overall usage rate of AI Coding Agent has increased.'' There are some parts of this story that are a little suspicious. When it comes to Rust, ClaudeCode and Codex have always been pretty competitive.
On the other hand, I think it's fairly accurate regarding C++. That's what I think.
As of 2025/12/01, there was a significant amount of Github Copilot, but it was gradually eaten up by Claude Code, and from around 2026/2/20, it can be seen that Codex has increased as a percentage. As a result, the new model of Codex has become able to write C++ accurately'', and as a result, the usage rate has increased'', and the overall usage rate of AI Coding Agent has increased accordingly. That's what I feel like.
Therefore, my understanding is that TypeScript, which has a high usage rate of AI Coding Agent among programming languages, is in a fairly even battle between Codex and ClaudeCode. However, Codex has become actively used in languages such as C++, which had been underused until now, and has gained market share. I think you can think of it that way.
thoughts
In March, the usage rate of AI Coding Agent accelerated unexpectedly. It was one month. That was my impression. On the other hand, what will happen to Claude Code? That's my honest opinion. Comparing ClaudeCode and OpenAI, OpenAI probably has more financial resources and is in a better position to create strong models. There is also a connection with Microsoft, and Github is under the umbrella of Microsoft. Therefore, it can be inferred that it has the ability to create models that are more coding-friendly than Anthropic. On the other hand, there are some doubts as to whether OpenAI should focus on the coding area. If anything, wouldn't their mission be better to create a type of AI that blends into everyday life rather than in the field of coding? I sometimes wonder, why are we putting so much effort into it? I have some doubts about this.
Another question is about Google. Regarding Google, I don't think Gemini is putting much effort into the coding area. However, in some sense this makes sense. From my point of view, Isn't OpenAI wasting too much AI investment in the coding area?'' On the other hand, Google is investing in Gemini as a whole, so coding is just one area.'' If you think about it, you may not see any point in taking a large share here. On the other hand, we are investing in devices such as smartphones that allow us to comfortably use AI built-in. When you think about it, the pie is bigger that way, so I think it's reasonable.
Also, is it okay for Github Copilot to have so many shares? There is a part of me that thinks so. However, since Microsoft has invested in OpenAI and is allowing OpenAI to be used through Azure, in the worst case scenario, there is a possibility that OpenAI will be acquired, so I guess Microsoft's camp has no chance of losing. There are parts of me that think so. Therefore, there is no problem even if Github Copilot has a low share. That's the idea. However, it is a futile battle as the allies are competing for territory. I can say that.
Recently, there has been a trend toward OpenClaw, and self-contained agents have become popular, and I feel that Claude Code is also heading in that direction. I feel like the surface of the board will change again in that area. Until now, such uses have been partially handled by Microsoft Copilot, etc., but I wonder if there will be a future where Claude Code becomes an agent rather than just for developers, and will be integrated into daily life like ChatGPT. That's what I think.