---
title: "AI Tokenizer"
description: "Count tokens and estimate costs across OpenAI, Anthropic, and other LLM APIs. Paste text or upload a file."
slug: "ai-tokenizer"
tags: ["AI", "LLM", "Tokenization", "Cost Estimation"]
url: "https://v0-tokenizer.vercel.app"
---


A free in-browser token counter and cost estimator for LLM APIs. Drop in a prompt, pick a model, and see token count, context utilization, and an end-to-end cost estimate — no signup, nothing leaves your browser.

## Features

- **Multi-provider model picker** — OpenAI (GPT-4o, GPT-4 Turbo, GPT-3.5), Anthropic (Claude Opus / Sonnet / Haiku), and more, with searchable list
- **Real-time token count** — Updates as you type, with characters, words, lines, and sentences
- **Context utilization** — Visual progress bar against the model's context window
- **Cost estimation** — Input + estimated output cost, configurable output tokens
- **Paste or upload** — Paste from clipboard or upload a `.txt` / `.md` file
- **Privacy-first** — Tokenization runs entirely client-side