Show HN: I built a free kids coloring site with AI(happykidscoloring.com)
happykidscoloring.com
Show HN: I built a free kids coloring site with AI
https://happykidscoloring.com/en
17 comments
Hi!
Nice work congratulations !
I have a question on how you generated the 2D line arts. You wrote that you used Google Gemini. I’m Interested to have more details on the prompt or the process you side it have quality line arts.
Thank you very much!
I have a question on how you generated the 2D line arts. You wrote that you used Google Gemini. I’m Interested to have more details on the prompt or the process you side it have quality line arts.
Thank you very much!
Thanks! I use Gemini's Imagen 3 API with specific prompts emphasizing "black and white line art, coloring book style, simple clean outlines, no shading".
Key is being very explicit about:
- Line art only, no shading/gradients - Age-appropriate complexity - Theme-specific keywords
Biggest challenge was consistency - took many iterations to dial in the prompts. I also manually filter out images with unwanted shading (working on automating this).
Happy to discuss more if you're exploring similar ideas!
Key is being very explicit about:
- Line art only, no shading/gradients - Age-appropriate complexity - Theme-specific keywords
Biggest challenge was consistency - took many iterations to dial in the prompts. I also manually filter out images with unwanted shading (working on automating this).
Happy to discuss more if you're exploring similar ideas!
I have a French website of place cards https://marqueplace.com that is up for more than 4 years but that I barely updated. I’m investigating an easy and cheap way to create alternative designs.
It’s all about creating simple designs that can be print in a flat card design. It’s very close to what you did. Obviously the immediate focus is Christmas and New Year’s Eve
Nice one, my daughter will love it. Have you thought about adding colored version done with some other ai to provide reference? my son (hes younger) prefers ones like that
Great minds think alike! I'm actually working on this feature right now - adding AI-colored reference versions alongside the line art. It should be live very soon. Thanks for the feedback, and I hope your daughter enjoys the current pages!
This is fantastic! Definitely bookmarking!
While I'm not one to suggest monetizing something that benefits a community I think you could reasonably monetize this by providing CaaS (ha! Coloring as a Service).
You could have weekly or monthly pdfs of generations emailed for particular themes like kids' school mascots, religious subjects like for Sunday school, curriculum subject correlating theme, etc.
Additionally, I would have it hide a signature somewhere in case someone starts scraping images and commercially selling them, or additionally license them to be able scrape them using Cloudflare.
While I'm not one to suggest monetizing something that benefits a community I think you could reasonably monetize this by providing CaaS (ha! Coloring as a Service).
You could have weekly or monthly pdfs of generations emailed for particular themes like kids' school mascots, religious subjects like for Sunday school, curriculum subject correlating theme, etc.
Additionally, I would have it hide a signature somewhere in case someone starts scraping images and commercially selling them, or additionally license them to be able scrape them using Cloudflare.
Oh! Another idea, have the uploading themes be a paid feature. I would consider site licensing for orgs. So if a school system wants to make it available to all teachers, they can pay a flat fee.
There's an incredible amount of potential with this! I'm jealous I didn't think of it!
There's an incredible amount of potential with this! I'm jealous I didn't think of it!
Great suggestions! I love the B2B angle - weekly themed PDFs for schools/organizations is something I hadn't fully considered.
For now keeping it free to build user base, but definitely thinking about premium tiers for: - Custom theme uploads - Organization licensing - Curriculum-specific content
The Cloudflare crawl protection is a good call too. Already using R2, so makes sense to add that layer.
Thanks for the thoughtful ideas - this is exactly why I posted here!
For now keeping it free to build user base, but definitely thinking about premium tiers for: - Custom theme uploads - Organization licensing - Curriculum-specific content
The Cloudflare crawl protection is a good call too. Already using R2, so makes sense to add that layer.
Thanks for the thoughtful ideas - this is exactly why I posted here!
AI Crawling protection
https://www.cloudflare.com/ai-crawl-control/
https://www.cloudflare.com/ai-crawl-control/
Feature request - a way to filter by age / difficulty from the home page. I see it on individual pages but didn’t quickly see the age listed as a tag. This is a point of friction on most coloring page sites. Congrats on this. I have bookmarked it. Thank you
For others who stumble upon this, another good free site without too many ads:
https://colorango.com/
For others who stumble upon this, another good free site without too many ads:
https://colorango.com/
Thanks for the feedback! Home page filtering for age/difficulty is now on my to-do list. Appreciate the bookmark and the kind words!
Nice!
Looks like something I built myself for my daughters, https://www.coloringsai.com
I am working on the categorisation as well now, is something difficult to do
Let me know if you need help with anything!
I am working on the categorisation as well now, is something difficult to do
Let me know if you need help with anything!
Sorry to be that guy.
I contemplated the same idea a while back because I'm constantly printing out colouring sheets for kids and it seemed like an app people would use.
Ultimately I decided not to build it because there are so many free colouring page sites out there, and there's a non-zero environmental cost to asking Gemini to generate a happy bat image.
Pretty much any colouring page a kid could ask you for is already a Google search away. In fact the challenge is not finding a happy bat colouring page but narrowing it down from the thousands of results.
I just don't see the value in using Gemini to add yet more generic colouring pages to the millions that exist. I'm sorry, I don't mean to poop on your work, it's interesting to read the tech implementation but ultimately I don't like creating walled gardens with AI generated alternatives to what's already free
I contemplated the same idea a while back because I'm constantly printing out colouring sheets for kids and it seemed like an app people would use.
Ultimately I decided not to build it because there are so many free colouring page sites out there, and there's a non-zero environmental cost to asking Gemini to generate a happy bat image.
Pretty much any colouring page a kid could ask you for is already a Google search away. In fact the challenge is not finding a happy bat colouring page but narrowing it down from the thousands of results.
I just don't see the value in using Gemini to add yet more generic colouring pages to the millions that exist. I'm sorry, I don't mean to poop on your work, it's interesting to read the tech implementation but ultimately I don't like creating walled gardens with AI generated alternatives to what's already free
No worries, these are fair points and I appreciate the honest feedback.
You're right - there are millions of coloring pages out there already. I thought about this too.
On the environmental cost: if no one uses it, I'll simply shut it down to save resources. That's a practical reality check. But if people do use it, then at least it means I've contributed something to kids' entertainment and education.
That said, my long-term vision isn't just "another coloring page site powered by AI." I'm working on integrating more interactive AI features - things like kids describing what they want and getting personalized pages, or uploading their own drawings to transform into coloring sheets. I want this to be something genuinely new and useful, not just a pile of AI-generated images competing with Google Image Search.
Whether I succeed at that differentiation remains to be seen, but that's the goal. Thanks for sharing your perspective - it's a good reminder to stay focused on creating real value, not just more content.
You're right - there are millions of coloring pages out there already. I thought about this too.
On the environmental cost: if no one uses it, I'll simply shut it down to save resources. That's a practical reality check. But if people do use it, then at least it means I've contributed something to kids' entertainment and education.
That said, my long-term vision isn't just "another coloring page site powered by AI." I'm working on integrating more interactive AI features - things like kids describing what they want and getting personalized pages, or uploading their own drawings to transform into coloring sheets. I want this to be something genuinely new and useful, not just a pile of AI-generated images competing with Google Image Search.
Whether I succeed at that differentiation remains to be seen, but that's the goal. Thanks for sharing your perspective - it's a good reminder to stay focused on creating real value, not just more content.
I built a free printable coloring pages website for kids, powered by AI generation.
The Fun Part: Almost all the code was generated by Windsurf with Claude Sonnet 4.5. This was an interesting experiment - I never thought I could actually pull this off. It's fascinating to see what's possible with AI-assisted development today.
Background: As a parent, I noticed my kids love coloring, but most online resources are either low quality or require paid subscriptions. So I built this using AI to provide high-quality coloring pages for free to all parents.
Core Features: - AI-generated high-quality line art (powered by Google Gemini) - 50+ themed categories (animals, holidays, nature, etc.) - Age-appropriate content (3-12 years) with difficulty levels - One-click PDF download, print-ready - Multi-language support (English, Chinese, etc.) - User favorites and browsing history
Tech Stack: - Next.js 16 + React 19 - Drizzle ORM + PostgreSQL - MeiliSearch for search - Cloudflare R2 for image storage - Google Gemini AI for content and category generation - Tailwind CSS + shadcn/ui
Interesting Challenges: 1. AI category consistency - Built a "memory system" to make AI reuse existing categories instead of creating duplicates 2. Image optimization - Using Next.js Image optimization with preloading strategy, LCP < 1.5s 3. SEO - Implemented structured data and multilingual sitemaps, now indexed 500+ pages on Google
Future Plans: - Custom AI generation from user prompts (text-to-coloring-page) - Image upload to generate coloring pages (image-to-coloring-page) - User upload and sharing features
Feel free to try it out and share your feedback! I'd especially love to hear suggestions on technical implementation and product direction.
The source code is not open-sourced yet, but happy to discuss technical details.