
Calendly
Acuity Scheduling
TidyCal
zcal
SavvyCal
SetMore
Doodle
Cal.com (formerly Calendso) is the open source Calendly alternative.
Smarty
Zipcodestack
PostalDataPI
Geoco.io
Melissa Data Quality
Loqate
usZIPCodes.org
REST API for US ZIP, ZIP+4, and Canadian postal codes. Single unified endpoint covers address validation and standardization, radius search (centroid haversine and true spatial polygon intersection), point-to-point distance, autocomplete/typeah

Which is more popular?
Based on our record, Cal.com seems to be more popular. It has been mentioned 60 times since March 2021.
Website, pricing, platforms and company facts side by side.
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ZIP
ZIP Code API
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| Website | cal.com | zip-codes.com |
| Pricing | — | |
| Company | — | Startup from the United States · 2026 |
| Listed in |
In their own words, as submitted to SaaSHub.

No description of Cal.com yet.
API for US ZIP, ZIP+4, and Canadian postal code data. One unified endpoint set covers North America — no separate APIs by country or data type. What it does Address validation and standardization — production-grade parser with ZIP+4 append, refreshed monthly Radius search — centroid haversine and...
What each product offers, as listed by its team.

Possible disadvantages
An editorial look at what each product does well and who it suits.

Overall verdict
Why this product is good
Recommended for
Overall verdict
Why this product is good
Recommended for
Walkthroughs and reviews on video.
What can you do with Cal? | Cal.com Version 1.1 Launch | 10 new languages
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How often each product is chosen within a category, 0–100% relative to the other.

Share your experience with using Cal.com and ZIP Code API. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.

The honest read: if you're leaving Acuity because your business outgrew simple scheduling — you need deposits, add-ons, multiple staff and locations, and ideally a booking site you own — Opencals is built for exactly...
I tried using https://cal.com for a bit but ended up just switching over to https://zcal.co and it has been great so far. All these other scheduling tools end up trying to do too much and always seem to end up a bit...
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Recommendations tracked on public social media and blogs since March 2021.

Then for the component library, I was really into coss ui. I stumbled upon it randomly one day and loved it so much. My Nathan's AI project already had a UI heavily inspired by cal.com: send button, message suggestions... So when I saw... - Source: dev.to / 7 months ago
I keep coming back to what would have happened if I didn't have a strong technical understanding of how calendar technology works — the difference between local and cloud calendars, what an ICS feed is, why enterprise auth blocks... - Source: dev.to / 7 months ago
Plausible brought open source to web analytics. Cal.com did it for scheduling. Formbricks did it for surveys. PostHog did it for product analytics. Quackback does it for feedback collection. - Source: dev.to / 8 months ago
Tracking ZIP Code API since May 2026.
When comparing Cal.com and ZIP Code API, you can also consider the following products.

Say goodbye to phone and email tag for finding the perfect meeting time with Calendly. It's 100% free, super easy to use and you'll love our customer service.
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Smarty provides address validation, autocomplete, geocoding and reverse geocoding services covering addresses in over 240+ countries.
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Automate your client bookings, cancellations, reminders & payments using the worlds friendliest online scheduling software.
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Free Zip Code API - Free Postal Code Validation | Zipcodestack
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Optimize your schedule with custom booking pages and calendar integrations
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The most affordable postal code API. 240+ countries, sub-5 ms responses. Simple, elegant, transparent.
Compare PostalDataPI to Cal.com or ZIP Code API: