USPS Developer Portal MCP. Audit addresses, track packages, and calculate rates in one conversation.
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USPS Developer Portal connects your AI agent directly to official United States Postal Service data. Verify addresses, calculate accurate shipping rates for domestic or international routes, audit package tracking history, and look up ZIP code metadata—all without leaving your chat client.
What your AI agents can do
Calculate domestic rate
Calculates the shipping cost for packages traveling within US domestic routes.
Calculate international rate
Determines the shipping cost for packages crossing international borders.
Get delivery commitments
Retrieves estimated delivery dates and service level commitments from USPS.
Standardizes and verifies any United States street address using official USPS web tools.
Retrieves the current status and detailed event history for a package using its tracking number.
Determines the real-time cost of shipping across various mail classes, weights, and global destinations.
Looks up the specific city and state associated with any given US ZIP code.
Queries live delivery commitments, providing estimated arrival dates based on mail class and service level.
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Supported MCP Clients
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USPS Developer Portal MCP Server: 8 Tools for Logistics Data
These eight tools give your AI client direct access to every core function of US postal logistics, from verifying addresses to calculating global shipping rates.
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Start using USPS Developer Portal on Vinkius019d8497calculate domestic rate
Calculates the shipping cost for packages traveling within US domestic routes.
019d8497calculate international rate
Determines the shipping cost for packages crossing international borders.
019d8497get delivery commitments
Retrieves estimated delivery dates and service level commitments from USPS.
019d8497lookup usps city state
Maps a known ZIP code back to its corresponding city and state pair.
019d8497lookup usps zip code
Finds the most accurate ZIP code for a given US street address.
019d8497track usps package
Checks the current status of a package using its main tracking number.
019d8497track usps package advanced
Retrieves detailed, facility-level event history for complex shipment auditing.
019d8497verify usps address
Standardizes and validates a full US address against USPS official records.
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Independent Platform Disclaimer: Vinkius is an independent platform and is not affiliated with, endorsed by, sponsored by, verified by, or otherwise authorized by USPS Web Tools. All third-party trademarks, logos, and brand names are the property of their respective owners. Their use on this website is strictly for informational purposes to identify service compatibility and interoperability.
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Works with Claude, ChatGPT, Cursor, and more
The Model Context Protocol standardizes how applications expose capabilities to LLMs. Instead of operating in isolation, your AI gains direct access to external platforms, live data, and real-world actions through secure, standardized connections.
This server provides 8 capabilities that interface natively with Claude, ChatGPT, Cursor, and any MCP client. No middleware. No custom integration required.
Manually checking addresses and calculating shipping costs sucks time.
Today, if you need to audit 50 customer addresses before generating labels, you copy/paste them into a spreadsheet. Then, for every single address, you might have to open the USPS website or another rate calculator tool just to verify it's correct and figure out the cost—a tedious loop of clicking, verifying fields, and cross-referencing data.
With this MCP server, your agent handles that whole process in a single prompt. You ask for validation on 50 addresses *and* the calculated domestic rate. The response is one clean block of verified metadata and accurate pricing. No manual clicks needed.
The USPS Developer Portal MCP Server: Get official USPS data without leaving your chat.
Before, tracking a package meant jumping between the carrier website, checking the status against a spreadsheet, and hoping the last update was accurate. If something looked wrong, you were stuck trying to figure out if it was a system error or a real delay.
Now, your agent uses `track_usps_package_advanced`. It pulls all the raw event data directly into your chat interface. You get the full audit trail—every scan, every facility stop. That level of detail changes how you resolve shipping disputes.
What you can do with this MCP connector
Your agent connects you straight to official USPS data. You don't need to juggle a bunch of websites—your client handles all the postal logistics in one conversation.
Verify US Addresses & Map Locations:
When you get an address from a customer, you gotta make sure it's legit and standardized first. Use verify_usps_address to validate any full U.S. street address against official USPS records; this guarantees your fulfillment metadata is spot-on. If you only have a ZIP code but need the city or state, run that through lookup_usps_city_state.
Need the proper ZIP code for a given street address? You'll use lookup_usps_zip_code to nail down the most accurate five digits.
Determine Shipping Costs & Timelines:
Figuring out shipping costs is simple. For stuff staying within the U.S., you call calculate_domestic_rate and it spits out the exact cost based on weight and destination mail classes. If you're sending packages across borders, use calculate_international_rate to get those overseas rates. You also need to know when it's gonna arrive.
Run a query using get_delivery_commitments, and your agent pulls live delivery commitments, giving you estimated arrival dates based on the service level you pick.
Track Packages & Audit History:
Checking where that package is? It's easy. You give your tracking number to track_usps_package, and it tells you the current status right now. But if you need the full story—like a proper audit trail for complex shipments—you use track_usps_package_advanced. This tool pulls detailed, facility-level event history, showing every single step the package took from origin to destination.
This setup means your agent handles everything: standardizing an address with verify_usps_address, finding the ZIP for a street using lookup_usps_zip_code, cross-referencing that ZIP code back to the city and state via lookup_usps_city_state.
When it comes to rates, you'll use calculate_domestic_rate for U.S.-only shipments or calculate_international_rate if you're sending stuff overseas. You can also get a timeline estimate with get_delivery_commitments, which provides those service-level dates.
For tracking, start by checking the status quickly with track_usps_package. But remember that for deep dives—for seeing every single facility scan and transfer event—you gotta use track_usps_package_advanced. It gives you the granular view of the shipment's entire journey. You don't have to open a browser or switch tabs; your agent just does it all in plain conversation.
019d8497-735b-7353-9c2e-0706ab32d49a 
How USPS Developer Portal MCP Works
- 1 Subscribe to the server and provide your USPS Web Tools User ID.
- 2 Ask your AI client a direct question (e.g., 'What is the cost to ship 5 lbs from NY to CA?').
- 3 The agent executes the necessary tool calls, gathers data, and returns a summarized, actionable answer.
The bottom line is: you talk to your AI client, and it handles all the required API calls to get a single, verified answer.
Who Is USPS Developer Portal MCP For?
Logistics Managers who spend too long manually verifying customer addresses. E-commerce Fulfillment Leads who need instant rate quotes before creating labels. Data Analysts building supply chain models that require precise postal metadata.
Verifies incoming customer shipping addresses using verify_usps_address and calculates the appropriate label cost with calculate_domestic_rate.
Tracks multi-leg shipments by calling track_usps_package_advanced to get full history, solving disputes over delivery timing.
Runs regional audits by using lookup_usps_zip_code and lookup_usps_city_state to build geo-coded datasets for market research.
What Changes When You Connect
- Accuracy: Don't guess on addresses. Use
verify_usps_addressto ensure every US location is standardized against official USPS records, preventing costly label errors. - Cost Control: Stop calculating shipping costs manually. Call
calculate_domestic_rateorcalculate_international_rateto get instant, accurate pricing based on weight and destination. - Deep Visibility: When a package gets stuck, don't rely on the surface status. Use
track_usps_package_advancedto pull granular, facility-level event data for full transparency. - Geo-Mapping: Need to know what area a code belongs to? Use
lookup_usps_zip_codeandlookup_usps_city_stateto map out regional logistics boundaries instantly. - Timing Guarantees: Before promising delivery, check the service level.
get_delivery_commitmentsprovides live estimates based on USPS mail classes.
Real-World Use Cases
Preparing for a Bulk Shipment Audit
The Operations Lead has 50 addresses from a new client, but they're messy. They run the list through the agent: 'Run verify_usps_address on these 50 locations.' The agent returns a clean CSV of standardized data, ready for label generation.
Debugging Delayed Deliveries
A client claims their package is late. Instead of just checking the status via track_usps_package, they run the advanced tool: 'Check full history for tracking number X.' The agent pulls detailed records showing exactly which facility stalled the shipment.
Calculating Dynamic Pricing
An e-commerce bot needs to show shipping costs in real time. It calls calculate_domestic_rate with the package dimensions and destination ZIP, getting an instant, accurate price that changes if the weight shifts.
Cross-Referencing Location Data
A data researcher needs to verify a region's postal structure. They prompt: 'What is the city and state for 98104?' The agent uses lookup_usps_city_state to confirm the location, adding precision to their database.
The Tradeoffs
Relying on surface-level tracking
Checking the status only with track_usps_package and seeing 'In Transit.' This tells you nothing about where it is or what happened last week.
→
Always use track_usps_package_advanced. That tool pulls all the granular, facility-level data. It gives you the full event log, not just a single status flag.
Guessing shipping rates
Using an old spreadsheet rate card or general web calculator for international shipments. These costs are constantly changing and rarely account for specific mail classes.
→
Always use calculate_international_rate. It hits the live USPS API endpoint, guaranteeing you get the current, accurate cost based on weight and destination.
Ignoring address standardization
Sending a label to an address that is only partially correct (e.g., missing 'Avenue' or misspelling a county). This guarantees it gets returned or delayed.
→
Run the full address through verify_usps_address first. It forces the data into the official USPS format, ensuring maximum deliverability.
When It Fits, When It Doesn't
Use this server if your workflow relies on precise, current U.S. postal logistics data—specifically tracking status, cost calculation, or address validation. If you are building an e-commerce platform, a fulfillment system, or any tool that needs to know where something is going or how much it costs to get there, this server is essential.
Don't use this if your task involves local municipal services (like city park permits), international postal systems outside the US, or general mapping without specific ZIP code verification. If you just need a list of major cities and states that aren't tied to USPS codes, a different database might be better. But for anything related to actual mailing, tracking, or rates, this is the definitive source.
Common Questions About USPS Developer Portal MCP
How do I use `verify_usps_address` with this server? +
You pass the full address string directly to your agent. The tool validates and standardizes it against official USPS records, confirming if the format is correct and usable for shipping.
`calculate_domestic_rate` or `calculate_international_rate`? Which one do I use? +
Use calculate_domestic_rate only when both the origin and destination are within the United States. Use calculate_international_rate for anything crossing US borders.
What's the difference between `track_usps_package` and `track_usps_package_advanced`? +
track_usps_package gives you the current, top-line status. The advanced tool provides a deep dive into the full event history—every scan location, date, and time—which is better for auditing.
Can I use `lookup_usps_zip_code` if I only have a general address? +
Yes. It takes a specific US street address and runs it through the system to find the most accurate, detailed ZIP code for that location.
How do I authenticate to run `verify_usps_address`? +
You must provide your USPS Web Tools User ID in the server setup. The agent uses this unique ID to authorize all calls, ensuring you are billed correctly and accessing the official data endpoints.
If I run `lookup_usps_zip_code` for an invalid address, what happens? +
The system returns a structured error code instead of failing. This prevents bad data from entering your workflow, allowing your agent to catch the failure and prompt you for correction.
Can I batch run `lookup_usps_city_state` for multiple ZIP codes? +
Yes, you can pass an array of ZIP codes as input. This handles bulk lookups efficiently, saving time when auditing large regional datasets.
When I call `get_delivery_commitments`, what format is the delivery estimate metadata in? +
The results arrive in clean JSON format. This structure makes it easy for your agent to parse and use the specific commitment dates or estimated service times.
How do I find my USPS User ID? +
Register for an account at the USPS Web Tools registration page. You will receive your User ID via email. Copy and paste it below.
Does it support international tracking? +
Yes. The track_usps_package tool supports tracking for any valid USPS tracking number, including international shipments originating from or delivered by USPS.
What is the format for address verification? +
The API requires an object with line1, city, and state metadata. Standardizing these inputs ensures the most accurate verification from the USPS database.
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