PostalDataPI
Smarty
Melissa Data Quality
CodeSignal
HackerRank
Codility
LeetCode
HackerEarth
Coderbyte
DevSkiller
iMocha
PostalDataPI is a global postal code validation and enrichment API covering 240+ countries and territories. One API, one key, one flat rate โ $0.000028 per query with no tiers or subscriptions.
What you get back: Up to 18 metadata fields per postal code โ city, state/region, coordinates, timezone, three levels of administrative hierarchy, elevation, and more. Sub-5ms cached responses.
Works everywhere: US ZIP codes, UK postcodes, German PLZ, Japanese postal codes, Canadian FSAs, and 230+ more. Format normalization handles case, spacing, and hyphen variations automatically.
Get started in 60 seconds: 1,000 free queries on signup, no credit card required. SDKs for Python and Node.js. MCP server for AI agents (Claude, Cursor, etc.).
Built for developers: REST API, consistent JSON responses across all countries, OpenAPI spec, llms.txt for AI agent discovery.
PostalDataPI
CodeSignalBased on our record, CodeSignal seems to be more popular. It has been mentiond 27 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
Mention tools like Slack, Zoom, GitHub Highlight remote work experience or team collaboration Link to your portfolio and GitHub Prepare for video interviews and live coding sessions (HackerRank, CodeSignal, etc.). - Source: dev.to / about 1 year ago
When I started, I programmed many different things in different languages. Then, I found a job as a Junior Java Developer and solved tasks on CodeSignal every day. - Source: dev.to / over 1 year ago
Platforms like HackerRank and CodeSignal host challenges that not only hone your skills but also can put you on the radar of tech companies looking for talent. - Source: dev.to / over 2 years ago
Regularly engaging with problem-solving and algorithm challenges on platforms such as LeetCode, HackerRank, or CodeSignal can significantly sharpen this ability. - Source: dev.to / over 2 years ago
Coding Challenges: Platforms like Project Euler or CodeSignal offer a variety of problems that encourage logical thinking and algorithmic problem-solving. - Source: dev.to / over 2 years ago
Smarty - Smarty provides address validation, autocomplete, geocoding and reverse geocoding services covering addresses in over 240+ countries.
HackerRank - HackerRank is a platform that allows companies to conduct interviews remotely to hire developers and for technical assessment purposes.
Melissa Data Quality - Melissa helps companies to harness Big Data, legacy data, and people data (names, addresses, phone numbers, and emails).
Codility - Codility provides a SaaS platform with advanced validation, security and protection features to evaluate the skills of software engineers.