AI Prompt Tester — Compare GPT, Claude, Gemini and More Side by Side
freeprompttester.app is a free, browser-based playground for running the same prompt across multiple AI models in parallel. You paste your own API keys for the providers you want to test, write a system and user prompt, pick up to six models from any combination of OpenAI (via OpenRouter), Anthropic, Google, xAI, Mistral, DeepSeek, Cohere and Groq, and watch each provider stream its response into its own card with time-to-first-token, total latency, token usage and per-call cost shown live. The OpenRouter tab also exposes the entire live catalog of 370+ models with provider sub-filtering and search.
freeprompttester.app supports two modes. Single-shot mode runs one prompt across up to six models in parallel and lets you click ✦ Synthesize to merge the completed responses into one combined answer with consensus and disagreement notes. Chat mode holds a parallel multi-turn conversation with up to three models, each maintaining its own history — the same user message produces divergent threads as turns accumulate, with cumulative cost shown per column.
Everything runs client-side. Your prompts and API keys are sent directly from your browser to each provider. No proxy server, no Freesuite middleman, no logging — you can verify it in the Network tab in your browser's developer tools.
How does freeprompttester.app compare AI models?
freeprompttester.app fans out parallel fetch() calls to each selected provider's chat completion endpoint when you click Run. Each response streams into its own card so you can read them as they arrive, side by side. After every call finishes, freeprompttester.app reads the input and output token counts returned by the provider and multiplies them by published per-million rates to show the exact cost of each call.
Why count tokens before sending a prompt?
Different models price input and output tokens differently, and the same English text can become 1.0× tokens on GPT-5, 0.95× on Claude Opus 4.7, and 1.6× on a Llama-based model. Without comparing them side by side, it is hard to know which model gives the best output-per-dollar for your specific workload. freeprompttester.app shows you the answer in one run.
Is freeprompttester.app free and private?
Yes. freeprompttester.app is free to use, has no sign-up, no ads and no tracking. Provider API costs are billed by each provider directly — Freesuite never sees the prompt, the response or the key. The page is a static HTML/CSS/JS bundle that runs in your browser; the only network traffic is the streamed response from each AI provider you select.
How accurate are the cost numbers?
Cost is computed from the token counts each provider returns at the end of the call (or in the streaming usage metadata) multiplied by the model's published per-million input and output rates. For models that don't return usage data in the stream, freeprompttester.app falls back to a calibrated character-based estimate — clearly labeled. Always check live pricing for production budgeting.
AI Model Comparison Matrix
| Model | Provider | Context | Input $/M | Output $/M | Access |
|---|
| Claude Opus 4.7 | Anthropic | 1M | $15 | $75 | Direct |
| Claude Sonnet 4.6 | Anthropic | 1M | $3 | $15 | Direct |
| Claude Haiku 4.5 | Anthropic | 200K | $1 | $5 | Direct |
| Gemini 2.5 Pro | Google | 1M | $1.25 | $10 | Direct |
| Gemini 2.5 Flash | Google | 1M | $0.30 | $2.50 | Direct |
| Grok 4 | xAI | 256K | $5 | $15 | Direct |
| Grok 4 Fast | xAI | 2M | $0.20 | $0.50 | Direct |
| GPT-5 | OpenAI | 400K | $1.25 | $10 | OpenRouter |
| GPT-5 mini | OpenAI | 400K | $0.25 | $2 | OpenRouter |
| GPT-4.1 | OpenAI | 1M | $3 | $12 | OpenRouter |
| DeepSeek V3.1 | DeepSeek | 128K | $0.27 | $1.10 | Direct |
| DeepSeek R1 | DeepSeek | 128K | $0.55 | $2.19 | Direct |
| Mistral Large 2 | Mistral | 128K | $2 | $6 | Direct |
| Llama 4 Scout 17B | Groq | 128K | $0.11 | $0.34 | Direct |
| Llama 3.3 70B | Groq | 128K | $0.59 | $0.79 | Direct |
| Command A | Cohere | 256K | $2.50 | $10 | Direct |
Prices last updated 2026-05-04. Always verify with each provider's pricing page.
Why use freeprompttester.app?
Bring your own keys
One key per provider. They live in localStorage, never on a server.
True parallel runs
Up to six models stream side by side. See TTFT, latency, tokens and cost.
Multi-turn chat mode
Parallel conversation across up to 3 models, each with its own history.
✦ Synthesize
Combine multi-model responses into one answer with consensus and disagreements.
370+ OpenRouter models
Live catalog with provider sub-filter and search. New models appear automatically.
No proxy, no logging
Static HTML page. Calls go browser → provider directly.
How it works
1. Add your API keys. Click "API keys" in the header. Paste a key for each provider you want to use. Keys are stored in your browser's localStorage and used only for direct provider calls.
2. Write your prompt. Enter a system prompt (optional) and a user prompt. Adjust temperature, max tokens and top-p if needed.
3. Pick up to six models. Click chips to select. Models from providers without keys are visually marked.
4. Run. Each model streams its answer into its own card with live token count, time-to-first-token, total latency and per-call cost.
Frequently Asked Questions
What is freeprompttester.app?
freeprompttester.app is a free, browser-based playground that runs the same prompt across multiple AI models in parallel. You paste your own API keys, write a prompt, pick which models to test, and watch each provider stream its response into its own card with latency, token usage and cost shown live. Everything runs client-side — keys and prompts never leave your browser.
Which models does freeprompttester.app support?
freeprompttester.app supports Anthropic (Claude Opus 4.7, Sonnet 4.6, Haiku 4.5), Google (Gemini 2.5 Pro, 2.5 Flash, 2.0 Flash), xAI (Grok 4, Grok 4 Fast, Grok 3), Mistral (Large 2, Medium 3, Small 3.1), DeepSeek (V3.1, R1), Groq-hosted Llama (Llama 4 Scout, 3.3 70B, 3.1 8B) and Cohere (Command A, R+, R) via direct browser calls, plus OpenAI's GPT-5, GPT-5 mini, GPT-4.1, o4-mini and any other model via OpenRouter.
Why does freeprompttester.app use OpenRouter for OpenAI?
OpenAI's API blocks direct browser calls (no CORS headers) so a static page like freeprompttester.app cannot call it without a proxy server. OpenRouter is a paid relay that does support browser calls and gives you access to OpenAI's models with a single key. Using OpenRouter keeps freeprompttester.app fully serverless while still letting you compare GPT-5 against everything else.
Where are my API keys stored?
API keys you paste into freeprompttester.app are saved in your browser's localStorage and used only to make requests directly from your browser to each provider. They never touch a Freesuite server. Anyone with access to your browser can read localStorage, so do not enter keys on a shared or public computer. Use the Clear all keys button to wipe them at any time.
Is my prompt sent to Freesuite?
No. freeprompttester.app is a static page. Your prompt is sent only to the AI providers you select, directly from your browser. There is no Freesuite server in the request path, no logging, and no analytics on input. You can verify this by watching the Network tab in your browser's developer tools while running a prompt.
How does freeprompttester.app calculate cost?
After each response finishes, freeprompttester.app reads the input and output token counts returned by the provider and multiplies them by the model's published per-million input and output rates. The cost shown per card is the cost of that single call. The run bar adds them up across all selected models so you can see total spend per run.
Can I compare more than two models at once?
Yes. freeprompttester.app lets you select up to six models per run. They stream in parallel into a responsive grid (two columns on desktop, one on mobile). Six is the soft cap to keep the UI scannable; for larger sweeps, run two batches and compare the saved JSON exports.
Does freeprompttester.app support streaming?
Yes. Every supported provider streams responses as they generate, and freeprompttester.app renders tokens as they arrive. Time-to-first-token is shown next to each card so you can see how fast each model starts producing output, not just total latency. Streaming can be disabled in settings if you prefer one-shot responses.
Does freeprompttester.app support multi-turn chat?
Yes. freeprompttester.app has a Chat mode where you can hold a parallel multi-turn conversation with up to three models simultaneously. Each model maintains its own conversation history, so the same user message can produce divergent threads as turns accumulate. The shared input bar broadcasts every message to all selected models, and per-column footers show cumulative cost and token usage as the conversation grows.
What is the Synthesize feature?
After running the same prompt across multiple models, click the ✦ Synthesize button to send all completed responses to a single chosen model. That model produces one combined answer plus a consensus section (where models agreed) and a disagreements section (where they diverged). It is useful for boiling down a multi-model run into one decision-ready output, with the agreement and uncertainty made explicit.
How many AI models can I access through freeprompttester.app?
freeprompttester.app exposes 25+ curated models across 8 providers via direct browser calls, plus the entire OpenRouter catalog of 370+ models with live pricing. The OpenRouter tab includes a provider sub-filter (Anthropic, OpenAI, Meta, Google, Mistral, DeepSeek, xAI, Qwen, Cohere, Perplexity, NVIDIA, MiniMax, and 50 more) and a search box to find any specific model by name or id.