Compare Claude vs GPT Side by Side — Live Output, Latency, Tokens, Cost

Choosing between Claude and GPT for a workload is rarely a single-axis decision. One model writes more concisely; the other reasons through edge cases more reliably; one is cheaper at high volume; the other is faster to first token. The only honest way to pick is to run your own representative prompts against both and read the outputs side by side. freeprompttester.app makes that a one-click comparison: paste your Anthropic key, paste an OpenRouter key (which gives you GPT-5), pick Claude Opus 4.7 and GPT-5 from the model picker, hit Run, and watch both stream into adjacent cards with TTFT, total latency, input/output tokens and per-call cost shown live.

Claude Opus 4.7 vs GPT-5 — at a glance

Pricing as of 2026-05. Always verify with each provider.

How to compare Claude and GPT with freeprompttester.app

1. Open freeprompttester.app and click API keys in the header.
2. Paste your Anthropic key (sk-ant-…) and your OpenRouter key (sk-or-…). Click "Test" on each row to verify.
3. Write a system prompt (optional) and the user prompt you want to test.
4. In the Models panel, switch to the Popular tab and click both Claude Opus 4.7 and GPT-5 (OpenRouter).
5. Hit Run. Both cards stream simultaneously. Read the outputs, compare TTFT and cost.

What to actually compare

Don't just read the answers. Look at:

• TTFT — time-to-first-token. If you're building chat UI, this matters more than total latency. GPT-5 typically lands faster on the first token; Claude Opus often catches up on long generations.
• Tokens out — terser is usually better. If two answers are equally good but one uses half the tokens, that one is also half the cost.
• Cost per call — shown in the card footer. Multiply by your volume to see whether the more expensive model justifies itself.
• Output quality — judged by you, on your prompt, in your domain. That's the whole point.

Tips for fair comparisons

Use the same temperature and max-tokens for both. Run the same prompt twice on each model to see variance. For long-context tests, paste a large document into the system prompt and ask a needle-in-haystack question — Claude Opus's 1M context window can hold things GPT-5 can't.

Comparing Claude vs GPT in chat mode (multi-turn)

Single-shot comparison reveals how Claude and GPT each answer one question. Chat mode reveals how they hold up across a 10-turn conversation — does Claude stay in character better, does GPT recover faster from "I changed my mind", which one tracks complex multi-step instructions cleanly. Open the Chat tab in freeprompttester.app, set one shared system prompt, pick Claude Opus 4.7 and GPT-5 (via OpenRouter), and start the conversation. Each model maintains its own history so the threads can diverge — you'll see exactly where they start to differ. Cumulative cost is shown per column (chat costs grow quadratically because each turn re-sends the full history).

Synthesizing Claude and GPT into one answer

After a single-shot run with both Claude and GPT, click ✦ Synthesize in the run bar to send both responses to a chosen synthesizer model. The synthesizer produces a combined best-of answer plus a consensus section (where Claude and GPT agreed) and a disagreements section (where they diverged, and which side seems more correct). For high-stakes prompts where you want both perspectives but a single decision-ready output, this collapses the comparison into one final answer.

Frequently Asked Questions

More Free Tools from Freesuite