For much of the past two years, Python's story in the TIOBE Programming Community Index was one of near-uninterrupted growth, culminating in the widest lead the index has ever recorded for a single language. That trend has reversed. The September 2026 TIOBE index put Python's rating at 17.76%, continuing a gradual decline that has played out over several months, according to TechRepublic's coverage of the index.

What actually changed

The shift is gradual rather than dramatic, and Python remains comfortably the top-ranked language on the index by a wide margin. But the direction matters: C also lost ground in September, slipping to 10.28%, while C++ edged up to 8.67% and further narrowed the gap with Java, which fell to 7.54%. Lower down the rankings, Julia has been creeping back toward the top 20 as MATLAB continues to slide — a smaller story, but one that reflects growing academic and data-science interest in Julia as a performance-focused alternative to Python for numerical work.

It's worth being precise about what the TIOBE index actually measures: it tracks how often a language is mentioned across search engines and related indicators, not how many developers use it day to day or how many job postings require it. A dip in TIOBE share doesn't necessarily mean Python is losing jobs or contributors — other surveys tracking active contributor growth, including GitHub's Octoverse data, have shown Python's contributor base growing at a double-digit rate even as TypeScript overtook it in total contributor count.

Reading the two data sources together

Put side by side, TIOBE's search-based ranking and GitHub's contributor-based ranking are telling a consistent underlying story even though their headline numbers differ: Python's dominance is no longer expanding, and multiple languages — TypeScript on the web development side, and compiled languages like C++ and Rust on the performance side — are gaining relative ground. Python isn't shrinking in absolute terms; it's facing more competition for the top of the index than it has in years.

What this means if you're planning what to learn

• Don't abandon Python. It remains the most widely taught, most widely used language for data science, AI/ML, and scripting, and that isn't changing. A declining index share is not the same as declining demand.
• Treat a second language as insurance, not a replacement. If your work touches performance-sensitive systems, web front-ends, or applications where typing and tooling matter at scale, adding TypeScript, Rust, or Go to a Python-based skill set is a stronger position than being a Python specialist alone.
• Watch the trend, not the snapshot. A single month's index movement means little. What's notable here is that the decline has now persisted across multiple consecutive readings, which is a different signal than normal month-to-month noise.

For most developers, the practical takeaway isn't to change course dramatically — it's to recognize that the language landscape is getting more competitive at the top, and that breadth across a couple of complementary languages is becoming a safer long-term bet than depth in just one.