Day & Zimmermann
Day & Zimmermann is a privately held, family-owned diversified industrial services company founded in 1901 and headquartered in Philadelphia, Pennsylvania. The company operates across four primary business segments — Maintenance & Construction (power, nuclear, fossil, renewable, and chemical plants), Munitions (ammunition manufacturing, storage, and demilitarization for the U.S. military, including operation of the Lake City Army Ammunition Plant), Government Services (security, EOD, facility management, and architecture/engineering for federal agencies), and Workforce Solutions (staffing and talent placement via Yoh). The Yoh family has controlled the company since 1961; Harold L. Yoh III serves as Chairman and CEO. Day & Zimmermann reported approximately $2.7 billion in revenue in 2023 with roughly 43,000–52,000 employees across approximately 150 global locations. Day & Zimmermann does not publish any public developer APIs; its business is delivered through long-cycle service contracts, government-owned contractor-operated (GOCO) facilities, and direct client engagements.
Index entry only — little beyond a description and a link, and nothing machine-readable enough for an agent to act on without a human reading the site first.
API Evangelist profiles Day & Zimmermann the way a machine reads it — 1 machine-readable artifact, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Day & Zimmermann scores 3.8/100 (minimal), with a separate agent-readiness read of 0/100 (human only). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance. Every facet and dimension name is a link: it opens that measurement's page on APIs.io, where the rating runs across the whole catalog — the exact checks that feed it, how every profiled provider distributes on it, and who is at the top of it.
Kin Score
How this is scored →scored 2026-09-08 · rubric v0.20.0
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<!-- Kin Score · API Evangelist -->
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title="Day & Zimmermann on API Evangelist — API profile and Kin Score">
<img src="https://apis.io/badge/day-zimmermann.svg"
alt="Day & Zimmermann Kin Score — API readiness rating by API Evangelist" width="150" height="150" loading="lazy">
</a>[](https://providers.apievangelist.com/providers/day-zimmermann/)<!-- Kin Score · API Evangelist -->
<a href="https://providers.apievangelist.com/providers/day-zimmermann/"
title="Day & Zimmermann on API Evangelist — API profile and Kin Score">
<img src="https://apis.io/badge/day-zimmermann/card.svg"
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How we profile Day & Zimmermann
Each block below is one kind of artifact we hold for Day & Zimmermann. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
Security Posture 1
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Resources
Every other property we hold for Day & Zimmermann — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Access & Security 1
Authentication, authorization, and security posture
Operate 1
Status, limits, changes, and where to get help
Company 6
The organization behind the API
Other 7
Properties that don't map to a standard resource type
Scroll within the panel for all 7 ·
← All providers · Data indexed from github.com/api-evangelist/day-zimmermann · machine-readable index on apis.io
This is an independent, third-party profile of Day & Zimmermann, published by API Evangelist. We do not operate, host, resell, or support these APIs, and we are not affiliated with or endorsed by the company unless stated above. Everything here is built from publicly available information — the company's own site, developer portal, documentation, public repositories, and the specifications it publishes for public use. Nothing is obtained by breaching a system, defeating an access control, or using credentials.
The Kin Score and Agent Readiness rating are independently calculated assessments of a company's public API artifacts, scored against a published rubric. They are not certifications, endorsements, security assessments, or audits.
Corrections, re-scores, and removal are free — no partnership or purchase required, and you do not need to justify the request. A removed company is recorded as unrated, never scored zero for having asked. Acknowledgement within one business day; removal within two.
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