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

NovoPsych
Clinical assessment tools for psychologists, therapists and occupational therapists. Send measures by secure link and review scored results, severity bands and reports.
Which is more popular?
Website, pricing, platforms and company facts side by side.
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ZIP
ZIP Code API
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|---|---|---|
| Website | zip-codes.com | clientforms.app |
| Pricing | — | |
| Company | Startup from the United States · 2026 | — |
| Listed in |
In their own words, as submitted to SaaSHub.

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...
Clinical assessment tools for psychologists, therapists and occupational therapists. Send measures such as the PHQ-9, GAD-7 and DASS-21 by secure link and get scored results, severity bands and reports ready to review. The catalogue also includes DSM-5 ADHD assessments and autism screening tools....
What each product offers, as listed by its team.

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
How often each product is chosen within a category, 0–100% relative to the other.

As answered by people managing ZIP Code API and ClientForms.app.
ClientForms.app's answer:
Frontend: Next.js 15 (React 19), Tailwind CSS Backend: Supabase (PostgreSQL, Row-Level Security) Authentication: Clerk Payments: Stripe Hosting: Vercel (Sydney region) Database hosting: Supabase (Australian data residency)
ClientForms.app's answer:
Psychologists who assess ADHD and autism. Typically private practice, solo or small group (1-5 clinicians), currently using paper forms and spending hours on admin per assessment. They want something that works and is secure.
ClientForms.app's answer:
Neurodivergent-first design. Most digital forms just replicate paper online. ClientForms is built specifically for ADHD and autism patients - progress bars with time remaining (helps with time blindness), softer colours instead of harsh white, sticky headers so you always know where you are. The forms are designed to reduce anxiety and improve completion rates.
ClientForms.app's answer:
Most clinical software treats patients as an afterthought. ClientForms is designed specifically for neurodivergent users who are filling out the forms, progress indicators, time estimates, calmer colours, predictable layouts. One link, no signup required, works on any device. Patients just open and complete.
Share your experience with using ZIP Code API and ClientForms.app. For example, how are they different and which one is better?
When comparing ZIP Code API and ClientForms.app, you can also consider the following products.

Smarty provides address validation, autocomplete, geocoding and reverse geocoding services covering addresses in over 240+ countries.
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NovoPsych is a tool that is used for outcome monitoring via conducting psychological tests online.
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Free Zip Code API - Free Postal Code Validation | Zipcodestack
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The most affordable postal code API. 240+ countries, sub-5 ms responses. Simple, elegant, transparent.
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ridiculously cheap bulk geocoding turn US street addresses into map coordinates and map coordinates into street addresses using our straightforward REST API
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Melissa helps companies to harness Big Data, legacy data, and people data (names, addresses, phone numbers, and emails).
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