DingDuff is a legal-research connector for Claude. It 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 right inside Claude, with citations.

DingDuff is listed in Claude's connectors directory, so adding it takes about a minute: find DingDuff in the directory, click add, sign in.

This wiki is written so you can either read it yourself or point Claude at it and ask Claude to walk you through everything. The easiest path:

Open Claude, paste the link to this page, and say: "Walk me through installing DingDuff, one step at a time."

⭐ Already installed? Read Account Settings for Optimal Use. Most users never turn on the settings that let DingDuff do its deepest research (the fetch_opinion_file tool). That one page is the difference between benchmark-grade results and a shallower answer — and it's the highest-value five minutes you'll spend with DingDuff.

• Install DingDuff (this page) — the main setup, start to finish.
• Account Settings for Optimal Use — the settings that let DingDuff research at full strength (personal vs. Team/Enterprise). Start here after installing.
• DingDuff with ChatGPT (beta) — how to connect DingDuff to ChatGPT instead of Claude (in beta; Claude is the primary, fully-supported experience).
• Browser Setup — extra steps if you use Claude in a web browser instead of the desktop app.
• Team & Enterprise — what to do if you're on a work plan and your admin controls connectors.
• Troubleshooting — fixes for common problems (a tool isn't working, you can't sign in, etc.).
• Skills & Settings — optional add-ons that make DingDuff noticeably better.
• How Citation Checking Works — what the cite-checker does, and the design behind its reliability and privacy.

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DingDuff itself is free. To use it you need two things:

1. A DingDuff login — sign up at https://dingduff.com to create your account. This gives you the email + password you'll use when connecting. DingDuff is for licensed attorneys (per the Terms of Service).
2. Your own Claude account — a paid plan (Pro, Max, Team, or Enterprise) is recommended. The Claude desktop app with Cowork mode is the best experience; a web browser also works (see Browser Setup).

Create the DingDuff account first. Step 2 below asks you to sign in with it, so having it ready keeps the install to one pass.

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Go to https://dingduff.com, click Sign Up, and create your account. Keep that email and password handy.

The quick way: open the DingDuff listing and click the add button:

https://claude.ai/directory/connectors/74942e30-fba3-4cfd-a381-75cf6a779c83

Or find it inside Claude:

1. In Claude, open Customize from the left sidebar (in a browser this may be under Settings), then go to Connectors.
2. Click the + button, then choose Browse connectors. The Directory opens.
3. Make sure Connectors is selected on the left, then type DingDuff in the search box.
4. On the DingDuff card, click the + to add it.

Either way, Claude then sends you to the DingDuff sign-in page. Enter the email and password for the account you created in Step 1 and approve the connection. You'll be returned to Claude automatically.

DingDuff is labeled a Community connector in the directory. That means it passed Anthropic's automated checks for the directory but wasn't individually reviewed by Anthropic — it works exactly like any other directory connector once connected.

A small browser/login window normally opens for sign-in. If nothing appears, see "Sign-in window doesn't open" in Troubleshooting.

On a Team plan you may see Request instead of an add button — that means your admin controls connectors. Click it and see Team & Enterprise.

After connecting, DingDuff appears in your connector list with its tools. We recommend setting each tool to always allow (the checkmark, not the hand icon) so you aren't asked for permission on every research request.

In a chat, ask Claude:

"Does the DingDuff connector have the opinion_search tool?"

If yes, the connector is working. Now try a real query, e.g.:

"Using only DingDuff, find recent Texas appellate cases on the economic loss rule and give me citations."

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Most users don't need this — skip it unless you're in a locked-down environment (read on).

DingDuff works best when Claude can save the full text of a case or statute to your working folder with fetch_opinion_file / fetch_statute_file and read the actual source. That needs Claude's code-execution environment with network access turned on (Settings → Capabilities → Code execution and file creation + Allow network egress; the desktop Cowork app already has it — see Browser Setup).

The BYOK (bring-your-own-key) path is for when you can't turn those settings on — e.g. a corporate Team / Enterprise account whose admin won't enable code execution or network egress. Without those, the store tools can't download files, so instead you add your own Anthropic API key to your DingDuff profile. That unlocks three tools that run on DingDuff's back end — opinion_extract, submit_batch_screen, and retrieve_batch_screen — which hand Claude focused excerpts of the relevant material, so it can read what matters without downloading anything and without flooding the chat with full opinions.

Which one applies to you?

• You can change Claude's settings (most Pro/Max users; Cowork desktop) → turn on code execution + network egress and use fetch_opinion_file / fetch_statute_file. Better results, no key needed. Skip BYOK.
• You can't change those settings (locked-down work account) → set up BYOK:
  1. Get an Anthropic API key from the Claude Console (console.anthropic.com) — add a payment method and create a key (ask Claude to walk you through it).
  2. Log in to your profile on dingduff.com and paste the key in.
  3. Use a dedicated key and turn off auto-reload (required by our Terms).

Cost is small — typically a few dollars a month, billed by Anthropic, not DingDuff.

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These take a few minutes and noticeably improve results. Full details on Skills & Settings:

• Install our skills via the DingDuff plugin — Customize → Plugins → under Personal plugins + → Add marketplace → Add from a repository → DingDuff/dingduff-public, then Install. That's all our skills at once, and new versions arrive through the marketplace instead of you re-downloading files.
  • Of the four, dingduff-legal-research is strongly recommended — DingDuff works without it, but noticeably better with it, because that skill carries the research method and most of our anti-hallucination instructions. The other three (legal analysis, citation check, citation formatting) are genuinely optional.
• Add a custom instruction (Profile → Instructions for Claude) telling Claude to always use DingDuff for legal research, so you don't have to ask each time.
• Turn off chat training in your Claude privacy settings.

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You can add the DingDuff connector on the Claude mobile apps the same way — the connectors directory is available there too — and research tools (searching and viewing cases, statutes, and PACER) work fine.

However, the features that need a working file environment — saving sources (fetch_opinion_file / fetch_statute_file) and the citation-check skill — rely on the desktop app or browser. For full functionality, use the desktop app (Cowork) or a browser; treat mobile as read-and-research on the go.

• A DingDuff "store" tool says it worked but no files appear → you likely need to turn on network access for Claude's tools. See Troubleshooting → Opinion/statute store tools don't work.
• DingDuff doesn't show up when you search the directory → see Troubleshooting → You can't add DingDuff from the directory.

For everything else, see Troubleshooting.