DingDuff links your own Claude account to a database of millions of court opinions, federal and state statutes and rules, and federal court filings (PACER) — so you can do real legal research, with real citations, right inside Claude. No new app to learn, no Boolean gymnastics: you ask Claude a legal question in plain English, and it searches the actual sources and answers with authority you can click through and verify.

"DingDuff is a must‑have for every litigator. Instead of spending hours devising Westlaw search terms, I can now get legal research through plain English prompts, just like working with an associate." — Michael Showalter, Litigator

Sign up at dingduff.com » · Installation guide (wiki) · Watch the 2‑minute demo · Skills library ↓

This repository is DingDuff's public home: the installation & help wiki and downloadable copies of the optional skills. To use DingDuff you connect it to Claude — start with the wiki.

• What DingDuff is
• What you can do with it
• What's covered
• The tools
• How it works
• The skills library
• Getting started
• Citation checking: reliable and private
• Who it's for
• What lawyers are saying
• Pricing
• Who's behind it

DingDuff is a connector (an MCP connector, in Claude's terms) that plugs a comprehensive legal database into the Claude you already use. Once it's added, Claude can search and read primary law directly — the same way a research associate would — and hand you answers grounded in citations rather than in its own memory.

We built DingDuff for our own daily practice, and the design philosophy shows: it gets out of the AI's way. We didn't wrap Claude in guardrails or try to teach it how to lawyer. We just gave it clean, direct access to the sources and let it work. In our hands that has consistently outperformed the purpose‑built legal‑AI products we used to pay for — enough that we quietly stopped using them.

The trade‑off is deliberate: because DingDuff is hands‑off, the lawyer reading the output is the guardrail. That's why it's built for attorneys, and why every answer is something you can open, read, and verify yourself.

Ask in plain English; Claude does the digging. For example:

• "Find recent Ninth Circuit cases on the economic‑loss rule and give me citations."
• "Pull the full text of Twombly and summarize the pleading standard it sets."
• "What does Texas Civil Practice & Remedies Code § 16.003 say, and what's the discovery rule around it?"
• "Show me every published opinion that has cited this case — is it still good law?"
• "Find the docket for this federal case and get me the motion to dismiss."
• "Research this question, then draft me an office memo — and cite‑check it when you're done."

The result is a research memo, a doctrinal map, a stack of saved opinions on your desktop, or a verified draft — whatever you asked for, with citations you can trust.

DingDuff draws on a database compiled largely from CourtListener (whose data heroes made this whole project possible) plus federal and state statutory sources:

Under the hood, DingDuff gives Claude a focused set of research tools. You never call these directly — Claude picks the right ones for your question — but here's what it can reach for:

• Search court opinions across federal and state courts, in plain English or with Boolean operators, filtered by jurisdiction, court, date, judge, or precedential status.
• Read the full text of any opinion, or get just the case metadata — court, date, precedential status, reporter citations, judges, and how many times the case has been cited.
• Trace the citation network: a built‑in citator finds every opinion that cites a given case, and surfaces related opinions on the same issue — so you can check whether authority is still good law and follow a doctrine forward and backward.
• Save your own copy of any opinion (full text) to a folder on your computer, so your research library is yours to keep.

• Search federal and state statutes, regulations, and court rules.
• Browse a code's structure the way you'd page through the book — title → chapter → section.
• Pull the exact text of a section, and save your own copy alongside your cases.

• Find dockets by case or by party / attorney.
• View a docket sheet, open individual filings, and search within a docket — or across many dockets — for the document you need.
• Check availability before you pull anything, and follow related docket entries.

• After you draft, verify every citation in the document against the actual source text and open an interactive review panel where you — the attorney — give the final verdict on each cite. (See below.)

From your side, it's three steps — and none of them are technical.

1. Connect it once. In your Claude account you add DingDuff as a custom connector (paste one URL, sign in with your DingDuff login). The wiki walks you through it — or you can paste the wiki link into Claude and have Claude walk you through it, one step at a time.

2. Ask Claude, in plain English. Once connected, you just ask legal questions the way you'd ask a colleague. Claude searches DingDuff, reads the real opinions and statutes, and answers with citations. (Tip: tell Claude to use only DingDuff and always give citations — you can set that once as a standing instruction so you don't repeat it.)

3. It adapts to where you run Claude:

• Claude Cowork (desktop app) — recommended. Claude can reach a folder on your computer, so instead of dumping opinions into the chat it saves your own full copy of each case and statute to a desktop folder you can revisit later. This is DingDuff at its best.
• The Claude web app or your phone. DingDuff runs here too — just switch on Claude's code‑execution and network settings (a one‑time toggle; the wiki shows you where) so it can save sources. On mobile, searching and reading work great; saving files and cite‑checking need the desktop app or a browser.
• Add the optional skills. Free, one‑time downloads that make Claude's legal answers noticeably sharper and more consistent.

We've never seen DingDuff hallucinate a fake case or statute — but Claude will occasionally get something wrong, which is exactly why a lawyer reads and checks the work.

DingDuff works well on its own. These free skills make it noticeably better — they teach Claude the craft of legal research, analysis, and cite‑checking. Each is a one‑time download that you upload to Claude once; it then lives in your skill picker and triggers automatically when relevant.

The research and analysis skills are designed to work together: research gathers the authority, and analysis reasons through the question to build the proof. Citation Check then verifies your finished work product; Legal Citation Format polishes the cites.

Install a skill: download the .skill file above (on GitHub, open the file and use Download raw file), then upload it to Claude —

• Cowork (desktop): Customize (upper‑right) → Skills → upload the file.
• claude.ai (browser): Settings → Capabilities → Skills → upload the file.
• Claude Code (CLI): install the whole library at once as a plugin:

  /plugin marketplace add DingDuff/dingduff-public
  /plugin install dingduff@dingduff
  

Skill files are named dingduff_<skill>_vX.Y.skill; in Claude's picker they appear under their dingduff-… name. To update, re‑download and re‑upload (or /plugin marketplace update dingduff). Citation Check needs python3, which Cowork and Claude Code provide.

You need two things:

1. Your own Claude plan. A paid plan (Pro, Max, Team, or Enterprise) is recommended; the desktop app with Cowork is the best experience. (The Free plan works but allows only one custom connector.)
2. A DingDuff login. Sign up at dingduff.com — this is the email and password you'll use to connect. DingDuff is for licensed attorneys, per the Terms of Service.

Then follow the installation wiki. The short version: add a custom connector in Claude pointing at

https://app.dingduff.com/mcp

sign in, allow the tools, and confirm it works by asking Claude "Does the DingDuff connector have the opinion_search tool?" The wiki also covers browser setup, Team/Enterprise plans, mobile, and troubleshooting.

DingDuff's citation checker takes a piece of legal writing you've drafted, checks every citation against the actual source text, and opens a review panel where you give the final word on each one — then produces a printable audit record for the file.

• Quotes are verified by code, not by the AI's memory. Claude proposes the supporting passage; a small program running in your own session then searches the real source file for that exact text. A made‑up or misremembered quote can't slip through as a verified highlight. (The matching forgives cosmetic differences — spacing, curly quotes, hyphenation across line breaks.)
• You see the evidence, and you give the verdict. For each citation you get the claim, the highlighted passage in the source, and your document side by side, and you mark it verified, needs attention, or rejected — with a note where useful.
• It's private by design. The checking runs entirely on your machine and sends nothing. The interactive panel passes your document through DingDuff only as the arguments needed to draw it, never stored or logged — and there's a standalone review.html if you'd rather nothing transit at all. DingDuff keeps no copy of your draft or your verdicts.

It checks against authorities you saved from DingDuff and any source you supply yourself — a Restatement section, a case that isn't in CourtListener, the other side's brief, a factual exhibit. Full explainer: How Citation Checking Works.

DingDuff is for lawyers. Its hands‑off design is the source of both its power and its one caveat: without heavy guardrails, Claude + DingDuff is remarkably capable, but it can occasionally get something wrong. With DingDuff, the attorney reading and checking the output is the guardrail — which is why a lawyer‑user is essential, and why we make DingDuff available only to licensed attorneys (you confirm this when you accept the Terms of Service).

"DingDuff is a game changer and I honestly can't imagine practicing without it. It has completely changed legal research for me from a slog to something I can complete in minutes. Even after spending hours doing research I was always worried I was missing something. And Westlaw's AI, while helpful, is still regularly incomplete or inaccurate. DingDuff is giving me confidence in my ability to do legal research quickly and thoroughly, and I use it daily in my practice. I also regularly get partner feedback that they are blown away by the research memos I put together using DingDuff and Claude. I can't imagine going back to a world without it." — Laura Bach, Litigator

"DingDuff is a must‑have for every litigator. Instead of spending hours devising Westlaw search terms, I can now get legal research through plain English prompts, just like working with an associate. I recently filed a thoroughly researched Ninth Circuit opening brief with DingDuff — without once opening Westlaw. It simply wasn't needed." — Michael Showalter, Litigator

DingDuff is free while in beta. Our running costs are low enough that we support the project with a tip jar rather than subscriptions — if it saves you time and you'd like to help keep it free, there's a tip option at dingduff.com. No subscription, no per‑search billing.

DingDuff started as a side project by two practicing lawyers — Kyle Dingman and Stephanie Duff‑O'Bryan — who wanted a research tool they could use in their own day jobs. It began as a scrappy interface to a database running on a Raspberry Pi in a closet; over a couple of years of iterating, it grew into something that (to our surprise) kept outperforming our firms' Westlaw‑AI accounts. We brought on developers Julia Teleki and Jeremy to turn a personal project into something we could share, and now we're making it available to other lawyers.

This project would not be possible without the data heroes at CourtListener / Free Law Project.

Links: dingduff.com · Installation & help wiki · Demo video · Terms of Service · Questions? hello@dingduff.com

Skills in this repository are developed in the DingDuff MCP server and vendored here for distribution; each dist/dingduff_<skill>_vX.Y.skill is a packaged copy of the matching plugins/dingduff/skills/dingduff-<skill>/ folder.