// api phase studio
We build APIs.
Sharp ones.
API Phase Studio is a developer infrastructure studio. We design and ship focused, production-grade APIs — each one built around a single problem, solved properly.
No bloat, no bundled SaaS platforms. Clean endpoints, honest pricing, and documentation that tells you exactly what you're getting. Built on proven open-source engines. Hosted. Ready.
API catalog
Available APIs
Each API is independently versioned and listed on RapidAPI. Try any endpoint directly from the listing — no setup required beyond a free key.
Phone Number Validator API
Validate, classify, and inspect phone numbers from any country. Built on Google's libphonenumber — the same engine used at scale in production. Pass a number in E.164 or national format with a region hint and get back structural validity, line type, carrier, geocoding, timezones, and every standard format representation.
Global Bank & Public Holiday API
Retrieve public and bank holidays for countries worldwide. Supports nationwide and subdivision-specific queries across 100+ countries using ISO 3166-1 alpha-2 country codes. Covers state, province, and regional holiday variations — so you're not flattening England, Scotland, and Wales into one result.
Readability Analysis API
Analyse English text readability across ten established formulas including Flesch Reading Ease, SMOG Index, Gunning Fog, Coleman-Liau, ARI, Dale-Chall, and more. Returns per-formula scores with grade levels, text statistics, and a multi-formula consensus when all methods are run — giving you a defensible, aggregate reading level rather than one formula's opinion.
About the studio
Built to solve
real problems.
API Phase Studio exists because most developer tooling is either under-engineered or wrapped in too much product. We pick hard, specific infrastructure problems — the kind that come up in production and don't have a clean off-the-shelf answer — and we build a focused API around each one.
Every API we ship is built on a proven, battle-tested open-source engine. We don't reinvent the math or the data model. We do the hosting, the versioning, the documentation, and the edge cases — so you don't have to spin up and maintain a service yourself.
More APIs are in development. If you have a use case that fits this model, the best place to reach us is through our RapidAPI listings.