🔬 TokenLens

Wanna see how AI chops your text into tiny weird pieces? This shows it.

Watch it do its thing :

Screen.Recording.2026-02-27.at.10.47.03.PM.mov

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What even is TokenLens?

AI doesn’t read like humans. It breaks stuff into tokens sometimes words, sometimes weird fragments, sometimes punctuation.

TokenLens lets you:

• See why prompts cost $$$
• Figure out why AI freaks out sometimes
• Compare how different models slice your text

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Features (or whatever)

• Colors for tokens (because why not)
• Token IDs, indexes, counts, ratios
• Shows API cost for GPT-4o, GPT-4, GPT-3.5 💸
• Flip between 4 encoders
• Updates as you type ⚡

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Supported Encoders

Encoding	Models	Vocab
cl100k_base	GPT-4, GPT-3.5-turbo	100k-ish
o200k_base	GPT-4o	200k-ish
p50k_base	text-davinci-002/003	50k-ish
r50k_base	GPT-2, GPT-3	50k-ish

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Run the Web App (super easy)

git clone https://github.com/your-username/TokenLens.git
cd TokenLens
python -m venv venv
# Mac/Linux
source venv/bin/activate
# Windows
venv\Scripts\activate
pip install -r requirements.txt
streamlit run app.py

Open http://localhost:8501 and watch the magic happen

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Run the CLI (also super easy)

For terminal lovers, TokenLens has a built-in CLI module.

# Tokenize direct text input
python -m tokenlens.cli "This is a test of the tokenlens engine."

# Pipe data from other tools
echo "Pipe me!" | python -m tokenlens.cli

# Check options
python -m tokenlens.cli --help

CLI Flags:

• -e, --encoder: Choose your encoder (e.g., o200k_base)
• -q, --quiet: Output just the integer token count for scripts
• --no-color: Disable ANSI color background output
• -s, --stats: Force show detailed stats/costs

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Token money stuff

Model	Cost / 1M tokens
GPT-4o	$5
GPT-4	$30
GPT-3.5-turbo	$0.50

Check OpenAI if prices matter.

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Why tokens even matter

• Tokens = text chunks (~4 chars each)
• BPE = AI’s way of merging bytes until vocab is big
• Costs, context windows, weird splits = all token stuff

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Project tree (looks organized, kinda)

TokenLens/
├── tokenlens/
│   ├── __init__.py   ← package marker
│   ├── core.py       ← tokenization heart
│   └── cli.py        ← the cool terminal tool
├── app.py            ← web app
├── requirements.txt  ← boring dependencies
└── README.md         ← this lazy thing

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License

MIT. Do what you want. Seriously.

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Built to learn. Inspired by tiktokenizer.vercel.app