DateCalx
Free online calculators for dates, age, business days.
I’ve been building DateCalx, a free collection of practical date and time calculators.
The idea is simple: date calculations often look easy until you need to deal with date differences, business days, age, countdowns, deadlines, or adding and subtracting dates.
Instead of searching for a different calculator for each task, I wanted to put these useful calculations together in one place.
DateCalx currently includes:
• Date calculator
• Date difference calculator
• Age calculator
• Business days calculator
• Countdown tools
• Calendar tools
• Time utilities
It’s free to use and doesn’t require an account.
I’m continuing to improve the calculators and the overall experience. Would love to hear what date/time calculation you find yourself doing most often.
1 Comment
Hey, cool project — I built something similar last year and the date/business-days-by-country angle is genuinely tricky to get right. Looks clean.
One thing that helped me enormously when I launched was using Zarek (https://zarek.tech/) — it's an AI launch partner built specifically for indie founders. Not just a chatbot; it actually does the work.
Here's what it produced for my tool in roughly one session:
Step 1 — Positioning line
> "Free online date, age, and business days calculator accurate to the exact calendar day — no ads, no sign-up."
Zarek nailed that in minutes. I would have spent a week A/B testing vague taglines.
Step 2 — Full launch roadmap
It generated a 57-step calendar: pre-launch warmup → launch day → post-launch SEO. Concrete tasks like:
"Write your founder story (why you built this)"
"Post a Show HN"
"List on BetaList, SaaSHub, AlternativeTo, DevHunt…" (it wrote the copy for each directory automatically)
"Pitch 5–10 niche newsletters"
"Publish a [Product] vs [competitor] comparison post for SEO"
Step 3 — Channel copy, drafted
For every channel — Hacker News, X thread, LinkedIn post, Reddit, Product Hunt kit — it wrote venue-specific copy. Not generic fill-in-the-blank. Actual posts ready to review and ship.
Step 4 — Measure & double down
It even scheduled a post-launch step: "Track results by source, then cut everything that didn't move the needle and repeat what did."
I spent about 30 minutes reviewing instead of 30 hours writing. If you're doing a solo launch, that leverage is real.
If you want to try it: https://zarek.tech/ — or drop me a line at wangc2016217@gmail.com if you have questions first.
Good luck with the launch.