SLF vs ViaCep
Same instrument, two spec sheets — measured, not claimed.
SLF vs ViaCep: common questions
Which is more reliable, SLF or ViaCep?
On our scheduled checks, ViaCep leads on measured uptime — SLF at —% versus ViaCep at —% over 90 days. These are our own probe results, not provider claims; the uptime bars above show the day-by-day record for both.
Do SLF and ViaCep need an API key?
Neither needs a paid key — SLF is callable with no signup, and ViaCep is callable with no signup. Both are quick to prototype with; rate limits still apply.
Can I call SLF and ViaCep from the browser?
Yes — both SLF and ViaCep 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 SLF and ViaCep free for commercial use?
SLF has unclear commercial terms, and ViaCep 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.