Building CheckHim – a Developer-Friendly API for Real-Time Phone Number Verification
Hi Indie Hackers! 👋
I’m Aristoteles, a developer living in São Paulo, and I just launched CheckHim — a developer-focused platform for real-time phone number verification.
💡 Why I Built It
Too many teams waste SMS/voice costs sending messages to invalid or unreachable numbers.
I wanted a lightweight, privacy-first API that lets developers decide early whether a number is worth contacting, before burning budget.
⚡ What It Does
Instant validation: format, carrier, line type, and deliverability indicators
Global performance: caching layers and regional routing for sub-100ms p95 latency
Actionable metadata: routing & risk decisions made easy
Developer experience: clear docs, sandbox responses, deterministic test numbers
🚀 Where I’m At
MVP live at checkhim.tech
Initial docs and sandbox ready
Working on roadmap items like bulk async verification, webhooks, and advanced risk scoring
🛠️ What I’m Looking For
I’d love feedback from fellow builders:
What features would make integration smoother for you?
Any pain points you’ve faced with phone number verification APIs?
Pricing models you’d expect (per request, monthly tiers, etc.)?
Thanks for reading!
Excited to learn from this community and share the journey as I grow CheckHim.
— Aristoteles
Very nice man, looks promising . just simple two questions:
1. Does it support validation for all countries?
2. Will you focus on validating only phone numbers? or care to expand to validate other types like emails, etc...? i think it will be great
Thanks Man
For now its only 10, but i'll gradually add other countries..
Yes, i want to expand it for other types..
That’s a really smart solution, Aristoteles — phone number validation is one of those small details that ends up saving teams huge costs over time. I like that you focused on performance and developer experience; sub-100ms latency and sandbox test numbers are exactly what make an API attractive to developers. The privacy-first angle also feels very relevant right now.
I also run a project called
birthday wishes for friends , which is all about structuring and delivering content clearly to users. Even though it’s focused on creative greetings rather than APIs, the principle is the same: if you make the experience fast, clear, and reliable, people are much more likely to adopt it. Wishing you success with CheckHim — it sounds like something that could see strong traction with startups.
Hey David, i'll check BWF too..
Man this means a lot, very thank you, hope guys use CheckHim one day.
This comment was deleted a year ago
I’m putting together a free SaaS Founder’s 7-Day Growth Blueprint — a step-by-step playbook to fix your landing page leaks, get traffic in 7 days, and turn trials into paying users.
Would you want early access?
Melanie Jumaga
It would be nice
Really cool idea. Please fix UI on mobile-first. Will still do further review, but the concept is really cool.
Means a lot, we'll apply the changes shortly
Few things, this space is crowded,but good concept. Not sure how you scale this to enterprice level.your mobile only landing page is disaster , fix that 1st. The pricing option is available but cannot see anything when I click on that. This is bad impression although it is MVP , you either have some message displayed as work i progress or dont give thag option at all.
Overall 1.8-2/5
Thanks for the advices...