litellm/litellm-rust/crates/token-counter

Token counting

Tokenizer is the text-counting interface. TokenCounter applies LiteLLM request, message, and tool accounting using any implementation of that interface

The fast feature provides fast::FastTokenizer from litellm-token-counter-fast. TokenCounter::from_json_fast uses this implementation

The huggingface feature provides huggingface::HuggingFaceTokenizer through the upstream tokenizers library. TokenCounter::from_json uses this implementation

The tiktoken feature provides tiktoken::TiktokenTokenizer through tiktoken-rs. Select an encoding with TokenCounter::from_tiktoken. The supported names are cl100k_base, o200k_base, o200k_harmony, p50k_base, p50k_edit, r50k_base, and gpt2

All three backends are enabled by default. The Python extension builds with fast only, which keeps the wheel at the size it had before the split. With default-features = false, callers can supply their own Tokenizer to TokenCounter::new without compiling a built-in backend

Budget checks, cost calculation, and the max_tokens adjustment policy belong to litellm-core-utils. The counter does not own prices, budgets, or request limits

Run the feature matrix with:

cargo test -p litellm-token-counter
cargo test -p litellm-token-counter --no-default-features
cargo test -p litellm-token-counter --no-default-features --features fast
cargo test -p litellm-token-counter --no-default-features --features huggingface
cargo test -p litellm-token-counter --no-default-features --features tiktoken