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.
This looks super useful! Traditional OCR tools often miss key details, so having a reliable API like Cardinal for structured data sounds like a game changer.
Feels like the tool thinks ahead. It not only reads documents but also structures them in a way I can use right away.
Using this has completely changed how I approach document workflows. Tasks that took hours now happen in minutes.
Handling large batches of files without slowing down is such a relief. It keeps my team moving fast.
The accuracy of the data extraction is impressive. Less time correcting errors more time getting things done.
This is dangerous… I was just here to browse and now I’m planning to redesign my cat’s food labels. Who knew design tools could be this fun?
Great!!! Documents with complex structures and relatively illegible fonts can be recognized! Perhaps the Cardinal has great potential in the restoration and preservation of ancient books!
About Cardinal on Product Hunt
“Build your document workflow with one API”
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.
Cardinal was featured in API (98k followers), SaaS (41.5k followers) and Developer Tools (511k followers) on Product Hunt. Together, these topics include over 115.3k products, making this a competitive space to launch in.
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.
Want to see how Cardinal stacked up against nearby launches in real time? Check out the live launch dashboard for upvote speed charts, proximity comparisons, and more analytics.
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