How I Built a Developer Tool That Saves 10 Hours/Week

It started with a simple frustration.
I was copy-pasting JSON from an API response into a TypeScript file for the third time that day. My hands hovered over the keyboard, about to manually type out another interface with 47 fields.
Then I stopped.
"There has to be a better way."
That thought changed everything. Six months later, I had built a tool that thousands of developers now use daily. This is that story.

The Problem I Couldn't Ignore

I'm a frontend developer. Or at least, I was supposed to be.
But I spent 10-15 hours every week doing mindless data conversion tasks:

Converting JSON API responses to TypeScript interfaces
Transforming JSON data into CSV for stakeholders
Generating mock data for testing
Reformatting JSON into YAML for config files

None of this was coding. None of it was creative. It was pure mechanical work that a computer should do.
One week, I tracked my time obsessively. Here's what I found:
Monday: 2 hours converting API responses to TypeScript
Tuesday: 1.5 hours generating CSV reports from JSON
Wednesday: 45 minutes creating mock JSON data
Thursday: 2 hours debugging malformed JSON
Friday: 3 hours updating TypeScript interfaces after API changes

Total: 9 hours and 15 minutes.

Nearly a quarter of my working week. Gone. Not building features. Not solving problems. Just converting data formats.
I did the math: At my hourly rate, this was costing my company $3,700 per month. Just for me. We had a team of eight developers, all doing similar work.
That's when I decided to build something.

The First Attempt (That Failed)
My first idea was simple: a Python script.

import json
import sys

def json_to_typescript(json_data):
    # Generate TypeScript interface
    # ...yeah, this got complicated fast

I spent three evenings on it. The script worked for simple JSON, but broke on nested objects. It couldn't handle arrays properly. Optional fields confused it. Union types were impossible.
After a week, I had a 400-line Python script that worked maybe 60% of the time.
My teammate saw me struggling and said, "Why don't you just use one of those online converters?"
I Googled "JSON to TypeScript converter."

Dozens existed.

My heart sank. Why was I reinventing the wheel?
But then I tried them. One by one.
Every single tool had issues:

• Slow page loads (ads everywhere)
• Requires sign-up or payment
• Ugly interfaces from 2010
• Only handles one conversion type
• Data sent to their servers (security concern)
• No dark mode (I code at night)

They worked, technically. But none were tools I wanted to use.
That's when I realized: the opportunity wasn't in building a converter. It was in building a converter developers actually enjoy using.

Building the Right Thing

I started with a simple philosophy:

Make it so good that I'd use it myself, every single day.

Principle 1: Privacy First

Most online converters send your data to their servers. For personal projects, fine. For work with proprietary API data? Not acceptable.
I made everything run client-side in the browser. Your JSON never leaves your computer. No servers. No logs. No risk.

Principle 2: Speed Obsession

I tested every competitor. They averaged 2-3 seconds to load the page before you could even paste your JSON.
I set a goal: instant. When you visit my tool, you can immediately start pasting. No loading spinners. No ads. No unnecessary cruft.

Principle 3: Actually Beautiful

Most developer tools look like they were designed in 1995. Gray backgrounds, Times New Roman, no polish.
I spent days on the UI. Dark mode default. Clean typography. Smooth animations. It should feel like a modern app, not a legacy tool.

Principle 4: Do ONE Thing Perfectly

Instead of building a "Swiss Army knife" tool that does 50 things poorly, I focused on doing JSON conversion perfectly.
Each converter got its own page. Each one handles edge cases. Each one gives clear error messages.

Principle 5: Free Forever

I was tired of "free trials" and "upgrade to premium" upsells.
Everything is free. No ads. No premium tier. No catch.
Why? Because I built this for me, and I hate ads. If it helps other developers too, that's just a bonus.

The Build Process

I'm not a designer. I'm not a UI/UX expert. I'm just a developer who's tired of ugly tools.
But I had Tailwind CSS, Claude AI for brainstorming, and a lot of determination.

Week 1: The Core Converter

I started with JSON to TypeScript because that was my personal pain point.
The algorithm had to handle:

• Nested objects
• Arrays of objects
• Optional fields vs required fields
• Union types (when values could be multiple types)
• Date strings
• Null values

The first version took 6 hours to build. It worked on my test cases.
Then I tested it on real API responses from projects I'd worked on.
It broke on 40% of them.

Week 2-3: Edge Cases

Every day, I'd find new edge cases:

• Empty arrays (how do you infer type from []?)
• Inconsistent data (array where objects have different fields)
• Circular references
• Very deeply nested objects (10+ levels)
• Special characters in field names

Each edge case took 30-60 minutes to handle properly.
This was the unglamorous part. Not building new features. Just making the existing feature work reliably.
But this is what separates a toy from a tool. Toys work on simple examples. Tools work on real-world data.

Week 4: The Other Converters

Once JSON to TypeScript was solid, I added:

• JSON to CSV (for stakeholder reports)
• JSON to YAML (for config files)
• JSON to Python (for backend team)
• JSON to SQL (for database work)

Each converter was 3-5 days of work. Same pattern:

• Build basic version (2-3 hours)
• Test on real data (1 hour)
• Fix edge cases (2-3 days)
• Polish UI (1 day)

Week 5-6: The Unique Feature

Everyone has JSON converters. I needed something no one else had.
I discovered TOON (Token-Oriented Object Notation) - a format optimized for AI/LLM usage. JSON wastes tokens when sending data to GPT-4 or Claude because of all the quotes and braces.
TOON is 30-40% more compact. For developers making thousands of API calls to OpenAI, this translates to real cost savings.
I built a JSON to TOON converter. To my knowledge, I was the first to make it easily accessible online.
This became my differentiator.

Launch Day

I didn't do a big launch. No Product Hunt submission. No Hacker News post.
I just tweeted: "Built a tool for JSON conversion. Try it if you need to convert JSON to TypeScript: jsontoall.tools

First day: 12 visitors.

All my Twitter followers (I had about 200 at the time).

First week: 89 visitors.

First month: 340 visitors.

Honestly? Disappointing.
I had spent 6 weeks building this. I expected... more. But the internet is noisy. Nobody cares about your side project until it proves useful.

The Turning Point

Two months after launch, someone posted about my tool on Reddit's r/webdev.
I didn't post it. A user found it, used it, and shared it organically.
The post got 200+ upvotes.

That day: 3,200 visitors.

My hosting bill went from $5/month to $40/month. Worth it.

That's when I realized: if you build something genuinely better, people will find it and share it.

The Growth Pattern

I didn't do marketing in the traditional sense. No ads. No SEO agency. No growth hacks.
Instead, I did three things:

1. Wrote Helpful Content

I published articles about JSON:

• "10 JSON Mistakes That Break APIs"
• "JSON vs YAML vs TOML: Which to Use"
• "Converting JSON to TypeScript: Complete Guide"

Each article naturally linked to my tool. But the articles were genuinely helpful, not just promotional fluff.

*2. Answered Questions
*
Every day, I spent 30 minutes:

• Answering StackOverflow questions about JSON
• Replying to tweets about data conversion problems
• Commenting on Reddit posts about development tools

When relevant (and only when relevant), I mentioned my tool.

3. Kept Improving

Every week, I added something:

• Better error messages
• Support for more edge cases
• New converter formats
• UI improvements

The tool got better every month. Users noticed.

The Numbers Today (6 Months Later)

Daily active users: 500-800
Total conversions performed: 47,000+
Countries: 20+
Revenue: $0 (it's free)
Time saved for users: If each conversion saves 5 minutes, that's 3,916 hours saved collectively.
My personal time saved: 10 hours/week, every week, for 6 months = 240 hours.
At my hourly rate, that's $18,000 in value. To me alone.

What I Learned

Lesson 1: Scratching Your Own Itch Works

I built this for myself. Everything I added was something I personally needed.
That authentic need translated into a better product. I wasn't guessing what users wanted. I was the user.

Lesson 2: Free and Fast Beats Complex and Paid

I could have built a SaaS with premium features, user accounts, team collaboration, and API access.
Instead, I built something simple, fast, and free.
The simple thing won. Because developers just want to convert JSON and move on with their lives.

Lesson 3: Quality Over Quantity

I could have rushed to build 50 mediocre converters.
Instead, I built 10 excellent ones.
People appreciate quality. A tool that works 99% of the time is infinitely better than one that works 80% of the time.

Lesson 4: Distribution Matters, But Quality Comes First

If I had launched on Product Hunt day one, I would have gotten some traffic. But the tool wasn't great yet.
By waiting until it was genuinely excellent, the organic growth was sustainable. Word of mouth only works if the product deserves the recommendation.

The Unexpected Benefits

Building this tool changed more than my workflow:

Career Impact

My GitHub profile now shows a real project with real users. When I interview for jobs, I have something tangible to discuss.
"I built a developer tool that 500+ people use daily" is a much better story than "I completed Leetcode questions."

Network Effect

Through this project, I've connected with:

• Other tool builders who reached out
• Companies that wanted to integrate my converters
• Developers who became Twitter mutuals
• Potential collaborators on future projects

Skill Development

I learned:

• How to handle edge cases systematically
• UI/UX principles that actually matter
• How to write clear error messages
• Performance optimization (those 500 daily users notice lag)
• Content marketing through helpful articles

These skills transfer to everything else I build.

The Honest Challenges

Not everything was smooth.

Challenge 1: Hosting Costs

As usage grew, so did costs. What started as $5/month is now $80/month.
I'm not making money from this. It's purely a cost.
But I view it as an investment in my portfolio and reputation. Plus, I use it daily myself.

Challenge 2: Feature Requests

Users want everything:

• "Add JSON to GraphQL schema converter"
• "Support JSON5 format"
• "Add team collaboration features"
• "Build a mobile app"

I can't build everything. Saying no is hard, but necessary.

Challenge 3: Maintenance

Code breaks. APIs change. Browsers update. Bugs emerge.
Even a "simple" tool requires ongoing maintenance. I spend 2-3 hours weekly just keeping things running smoothly.

Would I Do It Again?

Absolutely.
Not for the money (there is none).
Not for the fame (it's a niche tool).
But for these reasons:

• I use it every single day. Building something you personally use daily is incredibly satisfying.

• It helped hundreds of developers. The occasional thank-you email makes it worthwhile.

• I proved I could ship something. Finishing and launching a project builds confidence for the next one.

-** It opened doors.** Opportunities emerged that never would have if I hadn't built in public.

Advice for Aspiring Tool Builders

If you're thinking about building a developer tool, here's what I wish I knew:
Start With Your Own Pain

Don't build something because you think it'll be popular. Build something because you're frustrated by existing solutions.

Ship Fast, Improve Forever

My first version was rough. I launched anyway. Then I improved it every week based on real usage.
Perfection is the enemy of shipping.

Make It Free or Die Trying

Developers hate paying for tools. We're spoiled by open source.
If you can't make it free, you need an extraordinary value proposition.

Focus on One Thing

Don't build a platform. Build a tool that does one thing exceptionally well.
You can always expand later.

Write About What You Build

The articles I wrote brought more users than any other marketing channel.
Share your knowledge. Link to your tool naturally. Provide value first.

Listen to Users (But Not Too Much)

Pay attention to what problems users face. But don't build every feature they request.
Stay focused on your core value proposition.

What's Next

I have a list of 20 more converters I could build. JSON to GraphQL schema. JSON to Protobuf. Advanced validation tools.

But I'm being strategic. I'm focusing on quality improvements to existing converters before adding new ones.

I'm also working on a VS Code extension. Same converters, integrated into the editor. No context switching required.

The goal remains the same: save developers time on mindless tasks so they can focus on building great things.

The Real Win

Here's the thing nobody tells you about building tools:
The best reward isn't the user count or the GitHub stars or even the saved time.

It's the feeling of using something you built.
Every time I paste JSON into my tool, convert it to TypeScript, and copy the result - in three seconds flat - I smile.

Because I remember the days of manually typing interfaces. The frustration. The wasted time.

And I remember thinking, "There has to be a better way."
There was. I built it.

You can too.
The tool is jsontoall.tools. It's free, fast, and privacy-first. Built by a developer, for developers.

If you've ever spent hours on mindless data conversion, give it a try. It might just save you 10 hours this week.

What repetitive task frustrates you daily? Maybe that's your opportunity to build something people actually want.
Drop a comment - I'd love to hear about the tools you wish existed.