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tiktoken visualizer for o200k and cl100k
Online tiktoken-style visualizer for Exact OpenAI encodings: colored chips and token IDs for o200k_base versus cl100k_base on the same string.
What tiktoken visualizer means here
tiktoken is OpenAI’s widely used library for public encodings such as cl100k_base and o200k_base. A tiktoken visualizer shows encode and decode as colored chips with ids. TokenCalculator runs a gpt-tokenizer compatible path in the browser and labels the result Exact for those encodings only.
It is not a Claude tokenizer and not a Gemini tokenizer.
o200k_base vs cl100k_base
cl100k_base is common on many GPT-4 / GPT-3.5 turbo era paths. o200k_base is common on many GPT-4o / newer OpenAI chat paths. Always confirm the encoding for the exact model id. If both maps look totally different on one string, that is a vocabulary change, not a UI bug.
How to use it as a workbench
Paste production-shaped text. Select the encoding that matches the SKU. Read chips, IDs, and density stats. Flip encodings on a golden pack (English, code, JSON, emoji/CJK). Price with the cost calculator and catalog rates. Do not invent live $/1M prices.
What this visualizer is not
Not an Exact Claude piece map. Not an Exact Gemini piece map. Not a substitute for invoice usage when wrappers were omitted. Not a live price oracle. If a site paints Claude chips from tiktoken, treat those boundaries as fake.
Migration checklist
When moving from cl100k era models to o200k era models:
- Re-tokenize every template with Exact o200k chips
- Re-check context fit
- Re-price with catalog rates for the new model id
- Label screenshots with the encoding name
- Do not reuse old cl100k integers in finance models
Frequently asked questions
- What is a tiktoken visualizer?
- A UI that shows tiktoken-compatible encode/decode pieces as chips. TokenCalculator supports Exact o200k_base and cl100k_base at /tools/token-visualizer.
- What is the difference between o200k and cl100k visualization?
- Different vocabularies and merges. Same UTF-8 can become different chip lists and ids.
- Can I see token IDs in the browser?
- Yes on Exact OpenAI paths. Chip titles expose index and vocabulary id.
- Is there a tiktoken visualizer that shows chip colors?
- Yes: /tools/token-visualizer.
- Is the visualization Exact for Claude and Gemini?
- No. We do not draw fake Claude/Gemini boundaries. Use provider count APIs.
- Which encoding should I pick for GPT-4o?
- Prefer o200k_base for GPT-4o family models unless the provider documents otherwise for that exact model id.
- Can I use this visualizer as a Claude oracle?
- No. That pattern often causes double-digit planning error. Use Anthropic count_tokens.
- Does Exact mean my full API call matches?
- Exact means exact for the pasted string and encoding. Missing system, tools, or chat wrappers still undercount production.
- How do I compare OpenAI Exact rows to Claude Approx?
- Use tokenizer comparison, then verify Claude with Anthropic count_tokens before large commits.
- How does this help reduce prompt cost?
- Find dense chip regions, rewrite, then price with the cost calculator and catalog rates.
Try it in TokenCalculator
Paste one prompt, switch encodings, and compare Exact piece maps without leaving the browser.
Open token visualizer · Open tokenizer · Estimate API spend · All guides
Related tools
Token visualizer · Tokenizer comparison · Token counter · Tokens ↔ words
Related guides
Token visualizer: see colored token pieces · How LLMs split text into tokens · Code and emoji tokens · Exact vs fake boundaries
Sources and references
Official documentation used for definitions, counting methods, or rate cards. Always confirm critical budgets on the provider page.