You ordered it in the comments — so I built it: SoloPic, a free image tool

In my last piece, “Why I’m Rebuilding 100 Free Software Tools,” I closed with a question: Of all the free software you use every day, which one do you most wish someone would rebuild for you?

That wasn’t small talk. I genuinely wanted to know.

Then a comment came in. A reader from Tianjin, username Axiang. He didn’t write “keep it up” or “rooting for you.” He handed me a requirements list.

One comment, clearer than most spec docs

I’m copying his exact words here, unchanged:

How about a free image-processing tool? Here are a few things I need: First, batch crop — take a series of images and cut, say, 100px from the left edge and 57px from the bottom. Second, batch rename — you’ve got a series of files with names like 1.png, a.png, and so on, plus a text file (or something similar) that maps each file to its new name: 1.png,张三.png (newline) a.png,李四.png (newline), etc., and then 欻一下 (in a snap — his word) they’re all renamed. Third, batch adjust brightness, contrast, that sort of thing. That’s what I’ve got for now.

Look at that comment. It’s not vague. Not a single word of “could you guys make a better image tool” — the kind of correct-but-useless feedback that says everything and nothing. He gave three scenes specific enough to start building from right away:

• Crop 100px from the left, 57px from the bottom — he even gave exact pixel counts;
• A mapping file with “old name, new name” on each line, run it and they’re all done;
• Batch brightness and contrast.

My reply was one line: “Got it — the core is batch processing, right?”

He said: yes.

One exchange. A software’s requirements: set.

Why I knew immediately this was worth building

Because Axiang’s comment hit all three pain layers I described in “Rebuilding 100 Free Software Tools.”

Search “free batch image processing” and what do you get? A pile of things that either blast you with ads, lock “batch” — the only feature that matters — behind a membership wall, or install at a gigabyte and come bundled with three other pieces of software you never asked for. None of the three things Axiang wanted are technically hard. Every one of them is the kind of feature that should be free and easy to use — but has been turned into a hook. Batch rename: members only. Batch export: members only. Remove the ads by watching three more ads first.

This is exactly what I keep saying: “Rebuilding 100 free tools” isn’t about inventing 100 new gimmicks. It’s about taking the ones you use every day and just put up with, and rebuilding them into what they should have been. Axiang never read my internal list of candidates — but what he named was exactly what belonged on it.

So I didn’t overthink it. I finished typing “batch processing, right?” and went to build it.

What I built is called SoloPic

A few days later, it was live: SoloPic, a free, offline batch image tool weighing in at about 12 MB. It lives at solopic.doaipm.com — on my own subdomain, no app store required, no installer either: download the portable version, unzip, and run. GUI, command line, and MCP Server all bundled in. Windows for now; macOS and Linux are in the pipeline.

Everything Axiang asked for is there — built exactly the way he described it:

First, batch edge-crop. This is the one I most want to talk about. Most crop tools out there are built around one idea: resize all images to the same dimensions. But that’s not what Axiang needed. He needed to cut from the edge: no matter how big each image is, remove 100px from the left and 57px from the bottom. Varying sizes don’t matter.

You might wonder: trimming a fixed number of pixels from an edge seems simple — why is it worth calling out? Because it maps to a real scenario that existing tools consistently handle badly. Think about the kinds of batches you actually deal with: a pile of screenshots, each with the same-height status bar across the top; a batch of scanned documents with the same-width black border on the sides; a set of product photos with the same watermark stamped in the same corner. These images often aren’t the same size, but what you want to cut is “a fixed strip relative to one edge” — not “resize everything to 800×800.” With a fixed-size crop tool you have to align each image manually, and a few hundred of them can eat an entire afternoon. Axiang had clearly been through this — that’s how he got to “exactly 100px left, 57px bottom.” So I made edge-crop the default and used his numbers in the documentation. That’s not me being clever. That’s him pointing at the pain precisely enough.

Second, mapping-file batch rename. Write a list file — one “old name, new name” pair per line (e.g., 1.png → 张三.png) — and SoloPic reads it and renames everything in one go. And it previews before executing, with one-click undo — because the worst thing about batch rename is one wrong move scrambling an entire folder with no way back.

Third, batch adjustment. Brightness, contrast, saturation, sharpness, grayscale — drag a slider and hundreds of images change together, with a live split-screen before/after view while you’re dragging, not after you’ve already exported and noticed you went too far. This one sounds the most ordinary, but it’s exactly where most online image tools squeeze you: single-image adjustments are free, “batch” is a membership feature. Axiang included it because he knew from experience that images never come one at a time in real life.

That comment of his had a word — 欻一下, “in a snap” (it’s his phrase, not mine). I love that word. It captures the feeling of batch processing done right: everything handled all at once, just like that. So that’s exactly what I used as the tagline on SoloPic’s homepage: “Batch image processing — done in a snap.” Those words aren’t my copy. They’re Axiang’s.

What I actually did those few days

Some people might wonder: between one comment and downloadable software, what was going on in between? Honestly, it might surprise you: most of the time wasn’t spent writing code. It was spent getting clear on exactly what I wanted.

Take edge-crop. The first time I described it to the AI, I just said “make a batch crop tool” — and it gave me the obvious thing: resize all images to a fixed dimension. I had to go back and be more precise: not a uniform size, but cutting a fixed number of pixels inward from each image’s own edge, with each of the four sides configurable independently, working correctly even when image sizes vary. It took three rounds before it felt right. Same thing with the rename feature — I specifically added “preview before execute, one-click undo,” because I put myself in the user’s shoes: the reason someone would dare to batch-rename an entire folder is that they know they can undo it if something goes wrong. That’s not something the AI is going to think of — it takes someone who knows what users are afraid of.

So the real work those few days was small steps, one at a time: describe one feature clearly → let the AI build it → run it myself on a real batch of actual images → figure out what’s off and describe it more precisely → revise. Not one big dump of requirements, but pushing forward one verifiable piece at a time. This “say it clearly, take small steps, actually run it” approach is how I build every tool. SoloPic wasn’t any different.

I also added one thing he didn’t ask for

There was another comment in the thread, much shorter — just a product name: 扫描全能王 (CamScanner).

I knew what that meant. Apps like CamScanner are the classic case: point your phone at a document and it comes out looking like a scan — genuinely useful. But then exporting high-res costs money, removing the watermark costs money, ad-free costs money. Dropping that name in the comments was a way of saying: this one should have a non-extractive free version too.

My reply: “Got it, I’ll look into it.”

So SoloPic got a fourth feature — one Axiang didn’t ask for, but I built in while I was at it: smart document enhancement. A phone photo of a document — crooked, shadowed — becomes a clean scan in one tap: shadows removed, background whitened, text sharpened, skew corrected. Milliseconds, fully offline, no AI model required. This is my first step toward rebuilding CamScanner — I wanted to get the most essential piece in first.

Built for people and for AI

One more thing worth saying, because this is where the tools I’m building differ from ordinary free software.

SoloPic is one core engine, three ways to use it:

• GUI: browse to a folder, drag the sliders, see the before/after, click go. For Axiang, for most people, this is all you need.
• CLI: every feature is scriptable. The crop he wanted, for example:

pic crop --left 100 --bottom 57 D:\photos
pic rename D:\photos --map list.txt -x
pic enhance --mode bw D:\scans

• MCP Server: plug it into an AI assistant like Claude and you can just say it in plain language: “crop 100 pixels from the left side of everything in this folder” — and the AI calls SoloPic to do it.

Why build the last two? Because I’ve always believed one thing: going forward, software isn’t only used by people — it’s also used by AI. Axiang uses the GUI and drags the sliders. Someone who wants to plug image processing into an automated pipeline uses the CLI. Someone who’s used to talking to Claude just tells the AI directly. Same engine underneath, accessible to all three — that’s what genuinely useful looks like.

As for the ground rules of “free software,” SoloPic hasn’t broken a single one: free, MIT-licensed open source, completely offline, no network calls, no data collected, no ads, no installer needed. Your images are processed on your own machine. I never see them.

What this actually made me realize

After building SoloPic, the biggest thing I came away with wasn’t “I have one more tool.” It was something I hadn’t quite seen this clearly before — about what “rebuilding 100 free tools” actually is:

The 100 best candidates aren’t in my head. They’re in your comments.

The pain points I can think up on my own are limited — mostly the tools I happen to use every day. But Axiang’s “edge-crop and mapping-file rename”? Honestly, not scenarios I’d have thought of myself. Those come from someone who’s been batch-processing images for real, been ground down by the existing tools long enough to give requirements that precise. He doesn’t write code. But he knows better than anyone what that tool should look like.

Isn’t that the same thing I keep saying? Not knowing how to code isn’t a weakness. The hard part — the part that actually matters — is being clear about what you need. Axiang’s comment was a spec. A clear one. The rest was telling the AI to build it — a matter of a few days.

Flip the angle: this whole thing has turned the division of labor in “making software” upside down. In the past, even if a real user described their need with perfect clarity, it almost always disappeared into a void — because “find a team, spend money, wait months” was the barrier standing in the way. Nobody was going to move on a single comment. Between a need and a finished product, there was a wall that most people couldn’t get over. That wall is gone now. Axiang still doesn’t write code. I’m still not a big company. But a sentence specific enough, and a few days later it’s software running on his actual computer. What disappeared is exactly that wall.

So “rebuilding 100 free tools” feels less and less like a personal project, and more like something that can be crowdsourced for ideas: you know better than I do which free tools are the most broken, the most overdue for a real replacement. My job is to take the ones described clearly enough and turn them into something that doesn’t exploit you.

Keep the requests coming

Six became seven. SoloPic is the first tool in the “Rebuilding 100 Free Software Tools” series to be directly commissioned by a reader and built to order.

The more I do this, the more I think this is exactly how it should work: you make the request in the comments, I build it over here. You don’t need to know how to code, you don’t need to know anything about tech. You just have to do what Axiang did — take the free software that’s burned you the worst, and be specific: what’s it called, what do you want it to do, where does it get in your way.

I can’t fill the remaining ninety-three slots on my own with good ideas.

So I’ll ask again — and this time I mean it more: Of all the free software you use every day, which one do you most wish someone would rebuild for you? Write it out with some detail. It might be the next one I build.