Five Legal Data APIs Compared by What They Return
"Legal data API" is doing a lot of work as a category name. PACER, RECAP, UniCourt, and Trellis all get filed under it, and they answer almost none of the same questions.
Record breadth vs. judge-specific procedural depth
Qualitative placement based on each vendor's own public product description, not a scored benchmark
"Records" means dockets, opinions, and case data. "Rules" means structured, citable, judge-specific filing requirements, page limits, and formatting constraints, which is a different thing than analytics about how a judge tends to rule.
Every product on this list is good at the thing it was built for, which would be more reassuring if they had all been built for the same thing. Here's what each one actually returns when you query it, so you can tell which one you need before you sign anything.
PACER: the record of record, priced like it's 1998
PACER is where federal docket entries and filed documents legally live. It's the most complete federal record there is, and it charges $0.10 a page for the privilege of reading it, capped at $3.00 per document, a fee schedule that hasn't moved since 2020. There's no modern token-based REST API for pulling docket content, no webhooks, no delta feed. PACER's change-detection system is you, logging back in, ten cents a page. It knows everything that happened in a case and nothing about what a judge requires before you file the next thing.
CourtListener: the free archive with the biggest heart
Free Law Project's CourtListener is a donation-funded 501(c)(3) platform that liberates PACER data through its RECAP extension and layers on case law, judge biographical data, and financial disclosures, all queryable through a REST API that's free with a membership. For knowing who a party is, what a judge has published, or when a document was filed, it is excellent, and it pays for all of it by asking nicely. It has no field for a page limit, because a docket was never designed to hold one.
UniCourt: 4,000+ courts, price on request
UniCourt is the biggest number in this post: 4,000+ state and federal courts across 40+ states, by its own count, with a normalized dataset it markets as the largest structured litigation database in the country. Its self-described API-first platform and newer DEEP product are built for business development and litigation strategy, such as docket automation and party and firm analytics. The buyer is a business development team rather than an associate checking a standing order, and pricing is enterprise and not published. UniCourt is built for data breadth rather than for judges' filing rules, and it doesn't claim otherwise.
Trellis: knowing how a judge rules, not what they require
Trellis focuses on state trial courts and sells judge analytics: how a specific judge tends to rule on a given motion, verdict history, an opposing attorney's track record. Entry pricing starts around $69.95 a month, with a Lawyer plan around $120. Trellis tells you how a judge is likely to decide, which is a different question from whether your filing meets the judge's rules.
The side-by-side
| Product | What it actually is | Judge filing rules? | Pricing |
|---|---|---|---|
| PACER | Federal docket records, filed by the courts themselves | No | $0.10/page, $3.00 cap per document |
| CourtListener | Free case law, docket data, and judge bios (Free Law Project, nonprofit) | No | Free with membership; commercial agreements available |
| UniCourt | Normalized docket data and litigation analytics at scale | No | Enterprise, not published |
| Trellis | State trial court judge and litigation analytics | No (analytics on outcomes, not filing format) | From ~$69.95/mo |
| Court Rules | Judge-specific filing compliance, cited to page and section | Yes | Plan-based, REST + MCP |
The last question before you hit file
The four products above answer what happened in a case and what a judge is like. Court Rules answers whether a specific document meets a specific judge's rules before it is filed. Its coverage, 750+ judges across 20 districts, is the smallest in this post, so check whether the judge reading your filing is on the list.