Every developer I know has the same bookmark folder. It's called "converters" or "tools" or "dev utilities." Inside: a timestamp converter, a JSON to YAML tool, a base64 encoder, a color picker, a byte calculator, a cron expression parser.
Fifteen browser tabs you open at least once a week. Each one has:
- 12 tracker scripts
- A sticky newsletter popup
- A "before you leave" modal
- A CAPTCHA "just to make sure you're human"
- Probably some data collection in the background
We're developers. We have terminals. Why do we keep doing this to ourselves?
The problem with converter websites
Let me walk through a scenario. You're debugging a production issue at 2 AM. You have a Unix timestamp from the logs: 1748226460. You need to know what time that is.
So you open Chrome. Type "timestamp converter." Click the first result (because it's 2 AM and you don't care about SEO). The page loads:
- A full-screen interstitial ad for "10 Best Timestamp Tools of 2025"
- You click "Skip"
- A cookie consent banner slides up from the bottom
- A newsletter popup slides in from the left
- A "Hey, before you go!" modal prepares to ambush you when you leave
- You paste your timestamp, get the result, and close the tab
That's 6 seconds of friction for a task that takes 50 milliseconds. And you do this 5-10 times a week.
The math works out to roughly 30-60 minutes per week of loading, dismissing modals, and context-switching between browser and terminal. That's 26-52 hours a year. On converter websites.
Why CLI tools win
A CLI tool does the same thing in one line:
anyconv ts 1748226460
No browser. No ads. No CAPTCHA. No context switch. The output is already in your terminal — copy it, pipe it, grep it, script it.
CLI tools win on five axes:
1. Speed
A CLI command takes ~50 milliseconds to produce output. A website takes 2-5 seconds to load, render, and become interactive. That's 40-100x faster — for the same result.
2. Composability
Websites are dead ends. You paste data in, get a result, copy it, and paste it somewhere else. A CLI tool lives in your pipeline:
curl https://api.github.com/repos/amitwaks/anyconv | anyconv json yaml | grep description
You can pipe it, redirect it, capture it, script it, chain it. A website can't do any of this.
3. Privacy
Every time you paste a config file, an API key, or a JWT token into a random website, you're trusting that site not to log it, sell it, or leak it.
CLI tools run on your machine. The data never leaves. This matters when you're converting credentials, environment variables, or internal configuration.
4. Offline
Websites require a network request. CLI tools install once and work everywhere — on a plane, in a disconnected server room, in a Docker build step that has no external network access.
5. Stability
Converter websites have a lifespan. They get acquired, go offline, redesign their UI, start requiring login, or inject ads that break the functionality. A CLI tool installed from npm works the same way forever.
Building a CLI tool: lessons from anyconv
I built anyconv — a single CLI that replaces 50+ converter websites. Here's what I learned.
Start with the pain you actually feel. I didn't survey 100 developers. I looked at my own browser history and found the 6 converter sites I visited most. Those became the first commands: JSON↔YAML, timestamps, base64, colors, byte sizes, number bases.
Design for the pipe. The best CLI tools aren't destinations — they're transforms in a pipeline. Every converter reads from stdin or a file, writes to stdout, and does nothing else. No config files, no flags, no interactive prompts.
cat data.json | anyconv json yaml | grep "name:"
The interface should be invisible. When you type anyconv color ff0000, you don't think about the interface. It's just "convert this thing to that format." No --input, --output, --from, --to flags. The command structure is just <from> <to> [input].
anyconv json yaml file.json # clean. obvious. fast.
# not: anyconv --input file.json --from json --to yaml
Bundle size matters for CLIs too. Nobody installs a 200 MB tool to convert a color. anyconv is 5.5 kB gzipped — smaller than the hero image on most converter websites. It installs in under a second.
The bigger picture
This isn't really about converter websites. It's about a philosophy: the terminal is the best interface we have for developer tools, and most developer tools should be CLI-first.
Every time you reach for a browser-based tool, ask yourself:
- Could this be a CLI command?
- Could I pipe data into it instead of pasting?
- Could I script this into my workflow?
If the answer is yes to any of those, it's worth building or finding a CLI tool. The hours you spend context-switching between browser and terminal add up fast.
I built anyconv because I was tired of converter websites. I released it open source because I figured other developers felt the same way. Eight hundred npm downloads later, it turns out they did.
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