Cardinal is built for the hardest documents. Where LLMs hallucinate and miss structure, and traditional OCR tools are inaccurate, Cardinal delivers precise, structured data with bounding boxes you can trust.
Hi Product Hunt! This is Devi and Jianna, co-founders at Cardinal.
Today we’re launching the Cardinal API - the document workflow API for developers.
Cardinal is our second company together. Our first company, Leafpress, processed utility data. OCR was by far the hardest part - utility bills were very messy. We tried every tool we could think of and nothing solved our problem, so we finetuned our own VLM to process the data. That soon became Cardinal.
Unlike other mechanical OCR tools, Cardinal is more accurate. Unlike LLMs, we do not hallucinate and return high-quality bounding boxes. Cardinal gives you structured outputs that plug directly into your workflow.
Cardinal launched on Product Hunt on September 17th, 2025 and earned 127 upvotes and 5 comments, placing #16 on the daily leaderboard. Cardinal is built for the hardest documents. Where LLMs hallucinate and miss structure, and traditional OCR tools are inaccurate, Cardinal delivers precise, structured data with bounding boxes you can trust.
On the analytics side, Cardinal competes within API, SaaS and Developer Tools — topics that collectively have 650.6k followers on Product Hunt. The dashboard above tracks how Cardinal performed against the three products that launched closest to it on the same day.
Who hunted Cardinal?
Cardinal was hunted by Chris Messina. A “hunter” on Product Hunt is the community member who submits a product to the platform — uploading the images, the link, and tagging the makers behind it. Hunters typically write the first comment explaining why a product is worth attention, and their followers are notified the moment they post. Around 79% of featured launches on Product Hunt are self-hunted by their makers, but a well-known hunter still acts as a signal of quality to the rest of the community. See the full all-time top hunters leaderboard to discover who is shaping the Product Hunt ecosystem.
For a complete overview of Cardinal including community comment highlights and product details, visit the product overview.
Chris Messina
Hi Product Hunt! This is Devi and Jianna, co-founders at Cardinal.
Today we’re launching the Cardinal API - the document workflow API for developers.
Cardinal is our second company together. Our first company, Leafpress, processed utility data. OCR was by far the hardest part - utility bills were very messy. We tried every tool we could think of and nothing solved our problem, so we finetuned our own VLM to process the data. That soon became Cardinal.
Unlike other mechanical OCR tools, Cardinal is more accurate. Unlike LLMs, we do not hallucinate and return high-quality bounding boxes. Cardinal gives you structured outputs that plug directly into your workflow.
Endpoints available today:
Split – classify docs, break apart multi-page files, auto-detect types
Extract – enter your schema, get a custom JSON output
Markdown – get clean, readable text that preserves layout
RAG – chunk intelligently for retrieval and embedding workflows
Developers are already using Cardinal for fraud detection, healthcare claims, government contracts, and invoice processing.
You can start building right now:
Quickstart guide or Upload a PDF and test it out!
Excited to see what you build!
-Devi