TokenPath

TokenPath is an API service that adds token-level attribution to AI-generated text. You send it a source document, a question, an answer, and the claims you want verified. It returns the exact character positions in the source where each claim is grounded, along with a confidence score. The granularity goes down to individual tokens rather than just pointing at a whole document or paragraph.

The technical approach is attention-based. TokenPath reads the attention patterns from the model's generation process to trace which source tokens influenced which output tokens. That's different from asking the model to self-report its sources, which is notoriously unreliable. The attribution happens post-hoc, so it works with output from any LLM without modifying how you call the model.

Performance is competitive with Anthropic's Citations API. On the LongBench-Cite benchmark, TokenPath scores 0.815 F1 compared to Anthropic's 0.812. The claim is that it runs about seven times cheaper and five to six times faster at scale. For a 20,000-token document, attribution completes in under two seconds. It scales up to 128,000 tokens for long documents.

The API is RESTful and straightforward. You POST to the attribution endpoint with your document, question, answer, and claim spans. It returns source positions and confidence for each claim. There's also a heatmap endpoint that gives you the raw token-by-token attention matrix if you want to do your own analysis or build visualizations. Authentication uses a bearer token, and there's built-in rate limiting and usage metering.

Pricing starts with a free tier of 10 million tokens on signup, no credit card required. After that, it's $1 per million attributed tokens with no minimum spend. Volume pricing and dedicated deployments are available for enterprise use. That makes it accessible for prototyping and scales reasonably for production.

The target audience is developers building AI products that need auditable sourcing. RAG systems, legal document analysis, financial research tools, compliance workflows. Anywhere you need to show exactly where an AI answer came from rather than just trusting the model. You can reach sales at sales@tokenpath.ai or support at support@tokenpath.ai.