What shipping services does the USPS API support?

The API supports USPS Ground Advantage, Priority Mail, Priority Mail Express for domestic shipments, and Priority Mail International, Priority Mail Express International, and Global Express Guaranteed for international shipments.

How accurate are the shipping rates?

Rates are calculated in real-time using the official USPS REST API v3 with your actual origin and destination ZIP codes. Rates include dimensional weight calculations and zone-based pricing.

Does the API support international shipping?

Yes, the API supports international shipping to over 180 countries with automatic customs form requirements (CN22/CN23) and country-specific rate calculations.

Is there a rate limit on API calls?

The default rate limit is 60 requests per minute. For higher volume needs, contact us to discuss commercial rate limits.

What happens if the USPS API is unavailable?

The API automatically falls back to cached rates when the USPS API is unavailable, ensuring your checkout process continues to work.

What shipping services does the USPS API support?

The API supports USPS Ground Advantage, Priority Mail, Priority Mail Express for domestic shipments, and Priority Mail International, Priority Mail Express International, and Global Express Guaranteed for international shipments. All rates are calculated in real-time using the official USPS REST API v3.

How accurate are the shipping rates?

Rates are calculated in real-time using the official USPS REST API v3 with your actual origin and destination ZIP codes. Rates include dimensional weight calculations and zone-based pricing. The accuracy matches what you would see on usps.com.

What is dimensional weight and how does it affect pricing?

Dimensional weight (DIM weight) is calculated as (Length x Width x Height) / 166 for domestic shipments. USPS charges the greater of actual weight or dimensional weight. Our API automatically calculates this for you.

What are the maximum package dimensions allowed?

USPS has maximum dimensions: Length + Girth cannot exceed 130 inches, and no single dimension can exceed 108 inches. Maximum weight is 70 lbs. Our API validates these constraints and provides appropriate error messages.

Does the API support international shipping?

Yes, the API supports international shipping to over 180 countries with automatic customs form requirements (CN22/CN23) and country-specific rate calculations. Priority Mail International and Priority Mail Express International are available.

What customs information is required for international shipments?

For international shipments, you need to provide: content type (merchandise, gift, documents, etc.), item description, declared value in USD, and optionally an HS tariff code. Our API automatically determines if CN22 or CN23 forms are required based on value thresholds.

Are there any country restrictions?

Yes, USPS has restrictions and prohibitions for certain countries. Some destinations may have limited service availability or specific requirements. The API returns available services and any relevant restrictions for the destination country.

What is the API rate limit?

The default rate limit is 60 requests per minute per IP address. For higher volume needs, contact us to discuss commercial rate limits. The API returns a 429 status code with a Retry-After header when limits are exceeded.

What happens if the USPS API is unavailable?

The API automatically falls back to cached rates when the USPS API is unavailable, ensuring your checkout process continues to work. Responses include a "cached" flag to indicate when fallback rates are being used.

How do I authenticate with the API?

The public rate calculation endpoints do not require authentication. For advanced features like shipment tracking webhooks and audit logs, contact us for API key access.

What response formats are supported?

The API returns JSON responses by default. All responses include standard fields: success boolean, requestId for tracing, timestamp, and either data or error details.

What is Platphorm News Network?

Platphorm News Network is a suite of developer-focused APIs and tools including this USPS Shipping API, JSON Tree API for JSON parsing and validation, XML Tree API for XML processing, and MCP (Model Context Protocol) integrations for AI agents.

What is the JSON Tree API?

The JSON Tree API (json.platphormnews.com) provides endpoints for parsing, formatting, minifying, validating, and querying JSON data. It includes features like JSON diff comparison and JSONPath expressions. View the documentation at json.platphormnews.com/api/docs.

What is the XML Tree API?

The XML Tree API (xml.platphormnews.com) provides endpoints for parsing, formatting, and validating XML documents. It returns structure statistics, validates against XSD schemas, and supports various XML operations. View the documentation at xml.platphormnews.com/api/docs.

What is MCP integration?

MCP (Model Context Protocol) is a standard for AI agents to interact with external tools and services. Our APIs support MCP integration, allowing AI assistants like Claude to directly use our shipping rate calculation and data processing capabilities.

What is JA4+ fingerprinting?

JA4+ is a suite of network fingerprinting methods that help identify and track client connections. We use JA4H (HTTP fingerprinting) for audit logging and security purposes. This helps detect unusual patterns and potential abuse.

We log request metadata including timestamps, request IDs, client fingerprints (JA4H), response times, and error codes. We do not log the actual package contents or personal shipping addresses beyond what is needed for rate calculation.

How is my data protected?

All API communications use HTTPS encryption. We follow security best practices and do not store sensitive shipping information. See our Privacy Policy for full details.

Is the API free to use?

The basic rate calculation API is free for reasonable usage under our default rate limits (60 requests/minute). High-volume commercial users should contact us for enterprise pricing and increased limits.

Do you support donations?

Yes! If you find our APIs useful, you can support development via cryptocurrency. Our Coinbase wallet address is 0x30589F2e1B8E9a48BBb2c66Ac012FE7ED2A7eB85. We accept ETH and major ERC-20 tokens.

What about retail vs commercial pricing?

The API supports both RETAIL and COMMERCIAL price types. Commercial rates are available to businesses with USPS Commercial Plus pricing agreements. Select the appropriate priceType parameter in your requests.

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Frequently Asked Questions

What shipping services does the USPS API support?

How accurate are the shipping rates?

What is dimensional weight and how does it affect pricing?

What are the maximum package dimensions allowed?

Does the API support international shipping?

What customs information is required for international shipments?

Are there any country restrictions?

What is the API rate limit?

What happens if the USPS API is unavailable?

How do I authenticate with the API?

What response formats are supported?

What is Platphorm News Network?

What is the JSON Tree API?

What is the XML Tree API?

What is MCP integration?

What is JA4+ fingerprinting?

What data is logged?

How is my data protected?

Is the API free to use?

Do you support donations?

What about retail vs commercial pricing?

Technical Support

API Documentation