WhichAI v0.29 · Growth Private by design
WhichAI

The right AI for the job. The right prompt for it.

Describe your goal

WhichAI turns it into a prompt tailored to each AI model - and tells you which model is the best fit for the job, in plain language.

Uses your free API key to make the goal clearer and more complete - you review before applying.
Target models

AI assistants

Ecosystem assistants

Open models free/cheap via Groq & OpenRouter

Your optimized prompts will appear here - one version per model, plus a recommendation of which model fits this task best.

  1. 1 Describe your goal
  2. 2 Copy the prompt tailored to each AI
  3. 3 Compare the answers and iterate

No account · No server · Nothing leaves your browser

Model guide

Which AI app fits each kind of task - public benchmarks translated into plain language.

Compare

Run the same optimized prompt in each AI app, paste (or auto-run) the answers, and score them side by side. Everything stays in your browser.

No active comparison. Generate prompts first, then click "Compare outputs" to bring them here. Go to the Generator

Saved comparisons

Merge studio

Read every answer side by side and hand-pick the best parts into one final draft. Nothing is automatic - you stay the editor.

← Back to Compare

Chains

Break a complex goal into linked steps: each step gets its own optimized prompt, and the output of one step feeds the next. Auto-run steps where you have a free key; copy & paste elsewhere.

Saved chains

Settings

API keys enable automatic execution in Compare. Keys are stored only in this browser and are sent only to the provider you call - never to any WhichAI server (there is none).

How to get free API keys
  1. Gemini - open aistudio.google.com/apikey, sign in with Google, click "Create API key" and copy the key (starts with AIza…). No credit card.
  2. Groq - runs Llama - open console.groq.com/keys, create a free account, click "Create API Key" (starts with gsk_…).
  3. OpenRouter - open models - open openrouter.ai/keys, sign up free, click "Create key" (starts with sk-or-…). Model IDs ending in ":free" cost nothing.

Paste each key below, press "Test key" to verify it, then Save. Keys never leave this browser.

Where to keep API keys

Keys never reach any WhichAI server (there is none). "Session only" forgets them when the browser closes. Saving on this device uses browser storage, which any script on this page could read, so it stays opt-in.

Google AI Studio - runs Gemini

Default: gemini-3.6-flash (free tier). Change only if Google renames its models.

Groq - runs Llama

Default: llama-3.3-70b-versatile (free tier). See console.groq.com/docs/models for alternatives.

OpenRouter - runs open models (Nemotron, Qwen, GLM, Kimi, DeepSeek)

One free key unlocks auto-run for several open models. Model IDs ending in ":free" cost nothing (about 20 requests/min, 200/day). Get a key at openrouter.ai - no credit card needed.

Defaults are free routes: nvidia/nemotron-3-ultra-550b-a55b:free and qwen/qwen3-coder:free. GLM, Kimi and DeepSeek currently have no free OpenRouter route - leave empty to keep copy & paste, or set a paid ID (billed to your own OpenRouter credits) from openrouter.ai/models.

Preferences

WhichAI automatically remembers the last options you used in the Generator (models, task type, format, length, tone) and restores them next time.

Your data

Everything WhichAI saves lives in this browser: preferences, comparisons, chains, merge drafts and (if you chose so) API keys. Export a backup before switching device or clearing the browser.

Get free keys: Google AI Studio · Groq Console · OpenRouter. Claude and ChatGPT have no free API - for those, use Copy & paste in Compare.

About WhichAI

An open, free, sincere project with one goal: reduce the uncertainty of using AI - which model, which prompt, with evidence.

FAQ

Is WhichAI really free?

Yes, completely. No account, no subscription, no ads, no tracking. It runs on free hosting and the optional auto-run features use your own free API keys (Google AI Studio, Groq). There is nothing to sell you.

Where do my data and API keys go?

Nowhere. Everything (goals, prompts, comparisons, chains, keys) lives only in your browser. By default API keys are kept for the current session only; saving them on the device is an explicit opt-in in Settings. There is no WhichAI server. API keys are sent only to the provider you call (Google, Groq or OpenRouter), directly from your browser.

Why are generated prompts in English?

Every major model performs measurably best with English instructions. Each generated prompt includes a rule telling the AI to answer in the language of your task - so you can write your goal in any language and get the answer in your language, with English-optimized instructions doing the heavy lifting.

How reliable are the benchmark numbers?

Where public leaderboards publish a score (LMArena, SWE-bench, Artificial Analysis) we use it and link the source. Where they don't - private, preview, rumored or niche models - we show a clearly marked estimate ("~", "est."). Data is refreshed roughly monthly; the snapshot date is always shown.

What do the category scores and labels mean?

Each model in the database gets one overall score (Artificial Analysis Intelligence Index where published) plus four category ratings - Coding, Reasoning, Writing, Agents & tools - on a 0–100 scale. Category ratings are WhichAI blends of public category leaderboards and editorial judgment: use them to compare models at a glance, not as official measurements. Labels (like "free", "open weights", "in Generator") are filters: "in Generator" means you can generate optimized prompts for that model family right here.

Do I need API keys to use this?

No. Copy & paste works with every model. Keys only add convenience: with free Google AI Studio, Groq or OpenRouter keys, Compare and Chains can run Gemini, Llama and several open models (Nemotron, Qwen Coder…) automatically.

How does the model recommendation work?

A curated dataset translates public benchmarks into per-task rankings with a confidence level and linked sources. It is guidance, not gospel - near-ties are declared as ties, and the router never hides its reasoning.

Can I contribute?

Please do - see below. Ideas, corrections, new models for the database, translations: everything helps.

Similar tools - and what they do better

WhichAI is not the only prompting tool. In the spirit of openness, here is the honest landscape:

What WhichAI offers instead: prompts for 13 models from a single goal, benchmark-based model recommendations, side-by-side comparison and multi-step chains - 100% free, no account, everything in your browser.

Methodology v1.0

Updated: July 20, 2026 · next review with the monthly data refresh.

Limits: benchmarks are partial proxies of real work; snapshots age between refreshes; category blends involve judgment. When in doubt, run your own comparison in Compare.

Contribute & contact

WhichAI is open source and built in public. Suggest features, report wrong data, add models to the database, improve translations - or just say what confused you:

AI glossary

Every AI term in plain words - one sentence each, examples included.