TETR.IO vs Zelda
Same instrument, two spec sheets — measured, not claimed.
TETR.IO vs Zelda: common questions
Which is more reliable, TETR.IO or Zelda?
Both are neck-and-neck — TETR.IO and Zelda each measure 100% 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.
Which is faster, TETR.IO or Zelda?
TETR.IO has the lower median latency in our checks — TETR.IO responds in 357 ms versus Zelda at 903 ms (P50). Tail latency (P95) is in the table above; for most workloads the median is the number that shapes how the API feels.
Do TETR.IO and Zelda need an API key?
Neither needs a paid key — TETR.IO is callable with no signup, and Zelda is callable with no signup. Both are quick to prototype with; rate limits still apply.
Can I call TETR.IO and Zelda from the browser?
Yes — both TETR.IO and Zelda 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 TETR.IO and Zelda free for commercial use?
TETR.IO has unclear commercial terms, and Zelda 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.