Stamps.com

Stamps.com provides online postage and shipping services, enabling businesses and individuals to print postage, compare rates, and manage shipments directly from their computers. The platform integrates with major e‑commerce solutions, offers API access for automating label creation, tracking, and address verification, and supports bulk mailing, international shipping, and customs documentation. As a leading provider in the mailing industry, Stamps.com continuously expands its features to simplify logistics and reduce shipping costs for its customers.

Stamps.com is listed with 7 APIs on the APIs.io network, including Account API, Addresses API, Balance API, and 4 more. Tagged areas include Company, Shipping, E-Commerce, and Logistics.

The Stamps.com catalog on APIs.io includes 1 JSON-LD context and 1 Spectral governance ruleset.

Stamps.com’s developer surface includes documentation, API reference, getting-started guide, support, engineering blog, pricing, signup flow, and 17 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

26.4/100 thin ▼ -10.7 Agent 17/100 agent aware Heartbeat 100/100 alive Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

7 APIs

Company Shipping E-Commerce Logistics

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 26.4/100 · thin

Contract Quality 4.6 / 19

Developer Ergonomics 3.4 / 15

Access Clarity 3.4 / 15

Operational Transparency 1.8 / 10

Contract Governance 2.0 / 9

Discoverability 5.3 / 8

Regulatory Posture 2.2 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 17/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0

11 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 24.5 — up to +18.9 composite points
Developer Ergonomics scores 22.6 — up to +15.5 composite points
Access Clarity scores 22.4 — up to +15.5 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/stamps-com/apis.yml: open an issue on github.com/api-evangelist/stamps-com to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

OpenAPI

measured — observed by APIs.io (published)

APIs 7

Individual APIs this provider publishes, each with its own machine-readable definition.

Stamps.com Shipping API

REST and SOAP APIs for USPS shipping services, including rates, label creation, tracking, and address verification.

Stamps.com Account API

The Account API from Stamps.com — 2 operation(s) for account.

Stamps.com Addresses API

The Addresses API from Stamps.com — 1 operation(s) for addresses.

Stamps.com Balance API

The Balance API from Stamps.com — 1 operation(s) for balance.

Stamps.com Labels API

The Labels API from Stamps.com — 1 operation(s) for labels.

Stamps.com Stamps.com API

The Stamps.com API API from Stamps.com — 1 operation(s) for stamps.com api.

Stamps.com Tracking API

The Tracking API from Stamps.com — 1 operation(s) for tracking.

Scroll for all 7

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Stamps Com Context

11 classes · 35 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Stamps.com API Rules

13 rules · 9 errors 1 warnings 3 info

SPECTRAL

JSON Schema 6

Standalone JSON Schema definitions for this provider's data models.

GetV1V1IdResponse

3 properties

JSON SCHEMA

PostAddressesAddresseidResponse

8 properties

JSON SCHEMA

PostV1BalanceAddFundsResponse

3 properties

JSON SCHEMA

PostV1V1IdRequest

7 properties

JSON SCHEMA

PostV1V1IdResponse

10 properties

JSON SCHEMA

PutV1AccountSecurityQuestionsRequest

4 properties

JSON SCHEMA

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Stamps Com Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Resources

Get Started 3

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

SignUp

SignUp

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

WellKnown

WellKnown

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Spectral

JSONLD

Vocabulary

DataModel

Conformance

Access & Security 2

Authentication, authorization, and security posture

SecurityTxt

SecurityTxt

DomainSecurity

DomainSecurity

Operate 2

Status, limits, changes, and where to get help

StatusPage

StatusPage

Support

Support

Commercial 3

Pricing, plans, and the legal terms of use

PrivacyPolicy

PrivacyPolicy

Pricing

Pricing

TermsOfService

TermsOfService

Company 3

The organization behind the API

Newsroom

Newsroom

Website

Website

Blog

Blog

Other 2

Properties that don't map to a standard resource type

Hosts

Hosts

Vendors

Vendors

Source (apis.yml)

aid: stamps-com
name: Stamps.com
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  probe_state: none
  source:
  - security
  generated: '2026-11-06'
  method: derived
image: https://www.stamps.com/wp-content/uploads/2024/10/Stamps-Open-Graph-1200x1200-1.png
description: Stamps.com provides online postage and shipping services, enabling businesses and individuals to print postage,
  compare rates, and manage shipments directly from their computers. The platform integrates with major e‑commerce solutions,
  offers API access for automating label creation, tracking, and address verification, and supports bulk mailing, international
  shipping, and customs documentation. As a leading provider in the mailing industry, Stamps.com continuously expands its
  features to simplify logistics and reduce shipping costs for its customers.
url: https://raw.githubusercontent.com/api-evangelist/stamps-com/refs/heads/main/apis.yml
x-type: company
x-source: harvest:tag-qc
x-tier: profiled
x-tier-reason: enrichment pass 2026-10-13 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-10-13'
modified: '2026-10-13'
tags:
- Company
- Shipping
- E-Commerce
- Logistics
tags_raw:
- Company
- Shipping
- E-commerce
- API
- Logistics
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: PrivacyPolicy
  url: https://www.stamps.com/privacy-policy/
- type: Spectral
  url: rules/stamps-com-rules.yml
- type: JSONLD
  url: json-ld/stamps-com-context.jsonld
- type: Vocabulary
  url: vocabulary/stamps-com-vocabulary.yml
- type: DataModel
  url: data-model/stamps-com-data-model.yml
- type: Conformance
  url: conformance/stamps-com-conformance.yml
- type: LLMsTxt
  url: llms/stamps-com-llms.txt
- type: SecurityTxt
  url: well-known/stamps-com-status-security.txt
- type: WellKnown
  url: well-known/stamps-com-well-known.yml
- type: Hosts
  url: hosts/stamps-com-hosts.yml
- type: Vendors
  url: vendors/stamps-com-vendors.yml
- type: StatusPage
  url: https://status.stamps.com/
- type: Newsroom
  url: https://www.stamps.com/media/
- type: DomainSecurity
  url: security/stamps-com-domain-security.yml
- type: Website
  url: https://www.stamps.com
- type: DeveloperPortal
  url: https://developer.stamps.com/
- type: Documentation
  url: https://developer.stamps.com/
- type: APIReference
  url: https://developer.stamps.com/rest-api/reference/
- type: GettingStarted
  url: https://developer.stamps.com/
- type: Support
  url: https://help.stamps.com/hc/en-us
- type: Blog
  url: http://blog.stamps.com/
- type: Pricing
  url: https://www.stamps.com/pricing/
- type: SignUp
  url: https://www.stamps.com/signup/
- type: TermsOfService
  url: https://www.stamps.com/terms/
apis:
- name: Stamps.com Shipping API
  description: REST and SOAP APIs for USPS shipping services, including rates, label creation, tracking, and address verification.
  humanURL: https://developer.stamps.com/rest-api/reference/serav1.html
  baseURL: https://api.stampsendicia.com/sera
  aid: stamps-com:stamps-com-shipping-api
- aid: stamps-com:stamps-com-account-api
  name: Stamps.com Account API
  description: The Account API from Stamps.com — 2 operation(s) for account.
  humanURL: https://developer.stamps.com/rest-api/reference/serav1.html
  baseURL: https://api.stampsendicia.com/sera
  tags:
  - Account
  properties:
  - type: OpenAPI
    url: openapi/stamps-com-account-api-openapi.yml
  - type: JSONSchema
    url: json-schema/stamps-com-put-v1-account-security-questions-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-addresses-addresseid-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-get-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-balance-add-funds-response-schema.json
- aid: stamps-com:stamps-com-addresses-api
  name: Stamps.com Addresses API
  description: The Addresses API from Stamps.com — 1 operation(s) for addresses.
  humanURL: https://developer.stamps.com/rest-api/reference/serav1.html
  baseURL: https://api.stampsendicia.com/sera
  tags:
  - Addresses
  properties:
  - type: OpenAPI
    url: openapi/stamps-com-addresses-api-openapi.yml
  - type: JSONSchema
    url: json-schema/stamps-com-put-v1-account-security-questions-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-addresses-addresseid-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-get-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-balance-add-funds-response-schema.json
- aid: stamps-com:stamps-com-balance-api
  name: Stamps.com Balance API
  description: The Balance API from Stamps.com — 1 operation(s) for balance.
  humanURL: https://developer.stamps.com/rest-api/reference/serav1.html
  baseURL: https://api.stampsendicia.com/sera
  tags:
  - Balances
  tags_raw:
  - Balance
  properties:
  - type: OpenAPI
    url: openapi/stamps-com-balance-api-openapi.yml
  - type: JSONSchema
    url: json-schema/stamps-com-put-v1-account-security-questions-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-addresses-addresseid-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-get-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-balance-add-funds-response-schema.json
- aid: stamps-com:stamps-com-labels-api
  name: Stamps.com Labels API
  description: The Labels API from Stamps.com — 1 operation(s) for labels.
  humanURL: https://developer.stamps.com/rest-api/reference/serav1.html
  baseURL: https://api.stampsendicia.com/sera
  tags:
  - Labels
  properties:
  - type: OpenAPI
    url: openapi/stamps-com-labels-api-openapi.yml
  - type: JSONSchema
    url: json-schema/stamps-com-put-v1-account-security-questions-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-addresses-addresseid-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-get-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-balance-add-funds-response-schema.json
- aid: stamps-com:stamps-com-stamps-com-api-api
  name: Stamps.com Stamps.com API
  description: The Stamps.com API API from Stamps.com — 1 operation(s) for stamps.com api.
  humanURL: https://developer.stamps.com/rest-api/reference/serav1.html
  baseURL: https://api.stampsendicia.com/sera
  tags:
  - Stamps.com API
  properties:
  - type: OpenAPI
    url: openapi/stamps-com-stamps-com-api-api-openapi.yml
  - type: JSONSchema
    url: json-schema/stamps-com-put-v1-account-security-questions-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-addresses-addresseid-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-get-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-balance-add-funds-response-schema.json
- aid: stamps-com:stamps-com-tracking-api
  name: Stamps.com Tracking API
  description: The Tracking API from Stamps.com — 1 operation(s) for tracking.
  humanURL: https://developer.stamps.com/rest-api/reference/serav1.html
  baseURL: https://api.stampsendicia.com/sera
  tags:
  - Tracking
  properties:
  - type: OpenAPI
    url: openapi/stamps-com-tracking-api-openapi.yml
  - type: JSONSchema
    url: json-schema/stamps-com-put-v1-account-security-questions-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-v1-id-request-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-addresses-addresseid-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-get-v1-v1-id-response-schema.json
  - type: JSONSchema
    url: json-schema/stamps-com-post-v1-balance-add-funds-response-schema.json
x-coverage:
  state: none
  reason: no-developer-program
  method: derived
  generated: '2026-10-13'
  generator: derive-coverage.py (pre-flight evidence)
  detail: the company publishes no developer documentation host and no machine-readable contract on its own domain
  evidence:
  - url: https://www.stamps.com
    status: 200
x-enrichment:
  date: '2026-10-13'
  status: enriched
  artifacts_added: 20
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

Stamps.com API — frequently asked questions

Does Stamps.com have an API?

Yes. APIs.io lists 7 APIs from Stamps.com, including Stamps.com Shipping API, Stamps.com Account API and Stamps.com Addresses API, and 4 more.

Is there an OpenAPI specification for the Stamps.com API?

Yes. APIs.io indexes 6 OpenAPI specifications for Stamps.com, each linked for download from this page.

Is the Stamps.com API ready for AI agents?

Stamps.com has a Kin Score of 26.4 out of 100 (thin) and an Agent Readiness score of 16.5 (agent-aware), scored by API Evangelist on 2026-11-06.

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