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All toolsToken Boundary Visualizer
See how a prompt is tokenized with color-coded token boundaries.
This is an approximation showing typical BPE-style token boundaries. Counts will differ slightly from official tokenizers.
Text
Approx 28 tokens · 99 chars
The quick brown fox jumps over the lazy dog. Tokenization is approximate — real tokenizers use BPE.
Frequently asked questions
- Why does visualizing token boundaries matter?
- Seeing where tokens split reveals waste - leading spaces, unusual capitalization, or rare unicode can balloon counts. It also explains why some prompt edits change cost or behavior unexpectedly.
- Why does " hello" tokenize differently from "hello"?
- BPE tokenizers treat the leading space as part of the token, so " hello" and "hello" are typically two different token IDs. This is why mid-sentence words are cheaper than line-start words.
- Will the visualization match the provider's tokenizer exactly?
- It approximates the target family's tokenizer but may diverge on rare scripts, emoji sequences, or recent vocabulary updates. Treat boundaries as indicative, not authoritative.