After 8 months of daily use across 3 real projects, Claude wins for professional coding precision. ChatGPT wins for speed and breadth. Here's exactly what we found.
We ran 80 real coding tasks across both models, tracked pass rates, measured instruction compliance, and documented every failure. Here’s what we found — including where both models let us down.
Every score in this article is based on a documented test. We publish the exact prompts we used so you can run them yourself.
We used the default web interfaces (Claude.ai and ChatGPT) at temperature 1. We did not use system prompts. API results may differ. Both models update regularly — results reflect versions available in February–March 2025.
Each task was graded by two testers independently. A task was marked Pass only when the output ran without modification and satisfied all stated requirements. Partial credit was not given. Disagreements were resolved by a third tester.
We gave each model 20 Python tasks requiring correct logic on the first attempt — no follow-up prompting allowed. Tasks ranged from data pipeline transformations to async error handling.
created_at before deduplication, preserving the most recent record per user. Handled UTF-8 encoding errors with a try/except fallback without being asked.Silent logic errors are worse than crashes. If you’re running GPT-4o output in production without code review, this type of bug passes all syntax checks and only surfaces when you inspect the data. Claude’s 15-point advantage here is meaningful for data-critical work.
We wrote a single prompt with 7 explicit constraints and measured how many each model satisfied without reminding. Same prompt, 10 runs each, averaged.
The most commonly missed constraint was ⑦ unit tests — GPT-4o skipped this in 7 of 10 runs even though it was explicitly listed. Claude missed it in 2 of 10 runs. Constraint ⑥ error objects was the second most missed for both models.
We pasted a 900-line Python data pipeline and asked each model to modify only the HTTP request functions — without touching anything else. We then ran the full test suite to check for side effects.
The broken helper was in a different file section from the HTTP functions. GPT-4o appears to have “helpfully” cleaned up code it perceived as similar — a pattern we saw in 3 other large-file tests. Claude treated the scope constraint more literally.
We don’t only report where Claude wins. GPT-4o has real advantages that matter depending on your workflow.
Response speed. In our tests, GPT-4o returned first token 40–60% faster on average for short prompts. For interactive back-and-forth sessions this is genuinely noticeable.
Plugin ecosystem. GPT-4o integrates with hundreds of third-party tools through the ChatGPT plugin store. Claude has no equivalent. If your workflow depends on integrations (Zapier, Wolfram, code interpreters), GPT-4o is currently the only option.
General-purpose tasks. For writing emails, summarizing documents, or casual Q&A, we saw no meaningful difference between models. You don’t need Claude’s precision for these tasks.
| Metric | Claude 3.7 Sonnet | ChatGPT GPT-4o | Winner |
|---|---|---|---|
| First-try code accuracy | 80% (16/20) | 65% (13/20) | Claude |
| Instruction compliance (7 constraints) | 6.2 / 7 avg | 4.7 / 7 avg | Claude |
| Large codebase (no side effects) | Pass · 0 broken tests | Fail · 3 broken tests | Claude |
| Response speed (short prompts) | Slower | 40–60% faster | GPT-4o |
| Plugin / tool integrations | Limited | Extensive store | GPT-4o |
| Context window | 200K tokens | 128K tokens | Claude |
| General writing quality | Excellent | Excellent | Tie |
| Web interface price | $20 / month | $20 / month | Tie |
| API cost (per 1M input tokens) | $3.00 | $2.50 | GPT-4o |
The right answer depends on what you actually do, not on which model “won” the benchmark.