Use NSN Lookup inside Claude or ChatGPT
Connect once, then just ask. Your AI assistant looks up National Stock Numbers, part numbers and CAGE codes straight from the federal catalog data behind NSN Lookup, instead of guessing.
What you need
An NSN Lookup account
Free. Create one here if you don't have one. The free plan includes 1,000 lookups a month.
Claude or ChatGPT
Claude on the web, desktop app or phone (any plan). ChatGPT on the web or desktop app on a paid plan.
This one web address
You will paste it once. That's the only "technical" part.
https://api.nsnlookup.com/mcp Set up in Claude
Works the same on claude.ai, the Claude desktop app and the Claude phone app.
Open Connectors
In Claude, open Customize and choose Connectors. (Or open claude.ai/customize/connectors directly.)
Add a custom connector
Click Add custom connector and fill in two boxes:
NameNSN LookupServer URLhttps://api.nsnlookup.com/mcpAddSign in with your NSN Lookup account
Click Connect. A NSN Lookup sign-in page opens. Sign in and click Allow. You're returned to Claude.
Ask a question
Start a new chat and ask something like "What is NSN 5305-00-123-4567 and who makes it?". The first time, Claude asks permission to use NSN Lookup. Click Allow (or Always allow).
Using Claude for Team or Enterprise? Your organization owner adds the connector once under Organization settings > Connectors; then everyone clicks Connect. On Claude's free plan you can add one custom connector. To turn it on or off in a chat, click + > Connectors.
Set up in ChatGPT
Needs a paid ChatGPT plan (Plus, Pro, Business or Enterprise). On Business and Enterprise, your workspace admin may need to allow custom apps first.
Turn on developer mode (one time)
In ChatGPT, open Settings > Apps (called Connectors on some accounts) > Advanced settings, and switch on Developer mode. Despite the name, there's no coding involved.
Create the app
Back in Apps, click Create and fill in:
NameNSN LookupMCP server URLhttps://api.nsnlookup.com/mcpAuthenticationOAuth☑ I trust this applicationCreateSign in with your NSN Lookup account
A NSN Lookup sign-in page opens. Sign in, click Allow, and you're returned to ChatGPT.
Ask a question
In a new chat, click +, choose NSN Lookup (under More or Developer mode), and ask away. ChatGPT may ask you to confirm each lookup.
ChatGPT renames these menus from time to time. If a label doesn't match, look for "Apps", "Connectors" or "Developer mode" in Settings.
Things to ask once it's connected
"What is NSN 5305-00-123-4567, and who makes it?"
"Find the NSN for part number MS35338-44. What's the unit of issue and government price?"
"Here are 20 part numbers from an RFQ. Which have NSNs, and which CAGE codes are approved sources?"
"Which company is CAGE 1ABC2, and is the code still active?"
"What's the DEMIL code for this item and what does it mean?"
"What kinds of items are in Federal Supply Class 5305?"
Common questions
Is it safe?
Yes. NSN Lookup only lets the assistant read catalog data. It can't order, change or delete anything, and it never sees your NSN Lookup password. You can disconnect at any time from the same Connectors or Apps screen.
What does it cost?
The free plan covers 1,000 lookups a month. Each time the assistant looks something up counts as one. Heavy users can upgrade on the pricing page. Your Claude or ChatGPT plan is separate.
Why not just ask the assistant without connecting?
Without NSN Lookup, an assistant answers from memory or a web search and often gets NSNs, prices and CAGE codes wrong. Connected, it fetches the actual catalog record and can show you where the answer came from.
I'm a developer. Can I use an API key instead?
Yes. See the MCP developer setup (Claude Code, VS Code, Cursor) or the REST API quick start.
Something didn't work
Contact us and tell us which app you were using and which step stopped you. We'll walk you through it.
Ready? It takes about two minutes.
Make sure you have a free NSN Lookup account, then follow the steps for your assistant.
Create a free account Show me the steps again