▬▬▬▬▬▬▬▬  LLMKit
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LLMKit — Free AI & LLM Tools for Developers

Token counter · Model picker · Context window visualizer · API cost calculator · Prompt formatter · Temperature explorer · JSON Schema builder · System prompt library

→ Open LLMKit  ·  Report a bug  ·  Request a tool

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What is LLMKit?

LLMKit is a free, open-source suite of 8 browser-based tools for developers working with LLMs. No backend, no signup, no tracking — everything runs directly in your browser.

It's the all-in-one toolkit missing from the AI developer ecosystem: a token counter for GPT-4o, Claude and Gemini, a smart LLM model picker, a context window visualizer, an API cost calculator, and more.

Alternative to: OpenAI Tokenizer, tiktoken, context window charts, spreadsheet cost calculators, and scattered prompt engineering tools.

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🛠 Tools

Tool	Description
Token Counter	Count tokens for GPT-4o, Claude Sonnet, Gemini Pro and 6+ models. See input cost and context fill per model, in real-time.
Model Picker	Answer 5 questions → get the 3 best LLM recommendations for your exact use case (code, writing, docs, chatbots, data).
Context Window Visualizer	Paste your text and instantly see what % of each model's context window it fills. Warns when you exceed limits.
API Cost Calculator	Enter your request volume and token usage. Get monthly and yearly API cost estimates for every major model.
Prompt Formatter	Reformat any prompt for Claude (XML tags), GPT-4 (Markdown headers), clean text, or chat role structure.
Temperature Explorer	Slider from 0.0 to 2.0 with explanations, use case recommendations, and example outputs for each range.
JSON Schema Builder	Add fields visually → generate a valid JSON schema for LLM structured output, function calling, or tool use.
System Prompt Library	12+ ready-to-copy system prompts for developers, writers, analysts, and business — organized by category.

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Models covered

Provider	Models
OpenAI	GPT-4o, GPT-4o mini, o3
Anthropic	Claude Sonnet 4.5, Claude Haiku 4.5
Google	Gemini 1.5 Pro, Gemini 2.0 Flash
DeepSeek	DeepSeek V3
Meta	Llama 4 Scout

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Why LLMKit?

• ✅ Free forever — open-source, MIT licensed
• ✅ No signup — open and use immediately
• ✅ No server — 100% static, runs in your browser
• ✅ No tracking — no analytics, no cookies
• ✅ Always up to date — community-maintained model data
• ✅ Offline-capable — works without an internet connection after first load

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Usage

Just visit https://Fefefrost5.github.io/llmkit/ — no installation required.

Self-host in 3 steps

git clone https://github.com/Fefefrost5/llmkit.git
cd llmkit
# Open index.html in your browser — that's it

Or deploy to GitHub Pages, Netlify, Vercel, or any static host.

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Deploying to GitHub Pages (Windows)

1. Create the repository on github.com → New repository → name it llmkit
2. Upload files — drag & drop index.html, README.md, LICENSE, CONTRIBUTING.md into the repo
3. Enable Pages → Settings → Pages → Source: Deploy from a branch → Branch: main → folder: / (root) → Save
4. Your site is live at https://Fefefrost5.github.io/llmkit/ within ~2 minutes
5. Set repo topics (critical for SEO) → go to repo → click the ⚙️ next to "About" → add these topics:

llm  token-counter  ai-tools  prompt-engineering  developer-tools  
javascript  github-pages  openai  claude  gemini  chatgpt  
free-tools  static-site  llm-tools  context-window  api-cost-calculator

6. Set the homepage URL in About → Website: https://Fefefrost5.github.io/llmkit/
7. Replace Fefefrost5 with your real GitHub username in index.html (line 17, 30, 36) and this README

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GitHub SEO checklist

These steps will get the repo indexed and ranked quickly:

• Repository description set (under 350 chars, with keywords)
• All topics/tags added (see list above)
• Homepage URL set to GitHub Pages URL
• README has clear H1 and tool descriptions
• License file present (MIT)
• At least one release created

Suggested repo description:

Free browser-based LLM developer tools: token counter (GPT-4o, Claude, Gemini), model picker, context window visualizer, API cost calculator & more. No signup, no server.

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Contributing

Contributions welcome! See CONTRIBUTING.md for guidelines.

The most useful contributions:

• Update model pricing when OpenAI/Anthropic/Google change rates
• Add new models to the MODELS array in index.html
• Add system prompts to the SP_DATA array
• Report bugs via GitHub Issues

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Support

If LLMKit saves you time, consider supporting development:

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License

MIT — free to use, modify, and distribute. See LICENSE.