US ZipCode vs Zipcodestack
Same instrument, two spec sheets — measured, not claimed.
US ZipCode vs Zipcodestack: common questions
Which is more reliable, US ZipCode or Zipcodestack?
Both are neck-and-neck — US ZipCode and Zipcodestack each measure 0.0% uptime over 90 days on our probe schedule. Reliability here is verified from our own scheduled checks; use the 30-day bars above to see which has been steadier lately.
Do US ZipCode and Zipcodestack need an API key?
Both ask you to authenticate — US ZipCode uses an API key and Zipcodestack uses an API key. Each key is free to obtain; the Auth and Card-required rows above spell out the signup terms.
Can I call US ZipCode and Zipcodestack from the browser?
Yes — both US ZipCode and Zipcodestack send CORS headers over HTTPS, so front-end code can fetch either directly with no backend proxy. That makes them easy to swap in a client-side app while you compare responses.
Are US ZipCode and Zipcodestack free for commercial use?
US ZipCode has unclear commercial terms, and Zipcodestack has unclear commercial terms. We track service terms and the data license as separate fields — see the Commercial use and Data license rows above, and confirm both before shipping either in a paid product.