Code Comment Generator
Draft the code comments worth keeping: the ones that explain why a line exists, not what the syntax does.
This code comment generator drafts the kind of comment your team actually wants to find six months later, the ones that explain why a piece of code exists or what breaks if someone touches it. You paste a snippet or describe what the code does, pick the language and the comment style, and we scan for the risky parts: network calls, anything that looks like authentication, stray TODOs, magic numbers, config keys and failure handling. You name the future reader, the owner and the facts that must stay true, and we hand back a docblock, an inline note, a review comment, a config note or an owned TODO, plus a short alternative or two, a usefulness score and a review checklist. We never pretend every comment is worth keeping. Everything runs in your browser, so nothing you paste is uploaded.
100% in your browser. Nothing you type ever leaves this page.
Comment drafting, code-context analysis and review notes
This code comment generator drafts the comments worth keeping, the ones that explain why a piece of code exists rather than narrating the syntax line by line. You paste a snippet, or just describe what the code does, then pick the language and the comment style. We flag the risky parts, network calls, anything that looks like authentication, magic numbers, stray TODOs, and propose a phrasing or two you can paste straight in. You also get a usefulness score and a quick review checklist, so a docblock, an inline note or an owned TODO lands in good shape. Everything runs in your browser, so nothing you paste is uploaded.
Honestly? The best comment is sometimes no comment. Keep yours only when it says something the names or the tests just can't.
Good code comments explain the reason a reader cannot infer
Nobody tells junior devs this, so I will: a comment that translates code into English is worthless. I can read a loop. So can whoever inherits my mess. What none of us can read is the stuff that isn't in the file. Why a failure gets left visible on purpose. Why this one timeout gets babied while the rest don't. Why a config value that looks like a fat-fingered typo is actually load-bearing, or why that ugly workaround has to sit there until the platform team ships their fix. Write that down. The rest is noise.
That's the whole idea here. It asks the questions I ask myself before writing a comment: why does this even need saying, who reads it later, what facts have to stay true no matter how the code mutates. Then it scans your snippet and flags what usually deserves a note. Network calls. Anything that smells like auth. Stray TODOs, magic numbers, config keys, failure handling. It won't pretend every comment is a keeper, which I appreciate, because I sure don't. You get a better first draft. That's it.
When a comment is worth keeping
My rule of thumb: a comment earns its spot when editing the code without it would ship a bug or punch a hole in security. A docblock spells out what a function expects and how it fails. An inline note guards that one weird branch you'll forget the reason for by Friday. A review comment flags the bit you want a teammate to eyeball. And a config note? That's what stops someone copy-pasting your prod values straight into dev and then wondering why everything's on fire.
- Docblock when a function has intent and caveats worth pinning down up front, before anyone calls it.
- Inline note right next to that small decision that'll look plain wrong until you explain it.
- Review comment when the next move is a conversation in the PR, not a line in the source.
- Configuration note for the env and feature-flag stuff that bites you the second you change boxes.
- TODO with owner which is worth exactly nothing unless it names who's coming back to it, and why.
How to avoid comments that rot
Try the boring fixes first. Rename the variable. Split the function. Maybe write a test. Nine times out of ten the need for a comment just evaporates, and honestly I think most comments are a code smell wearing a hat, though I might be talking myself into that. If something genuinely unique is left over, keep it short. Don't describe the implementation: that's the exact thing the next refactor changes, and then your comment is quietly lying to people. Pin it to a reason instead. A contract, a limitation, some external system that misbehaves on a full moon, a bug you're guarding against. And if you can, write down when this comment stops being true, so the next person knows when to kill it.
Practical examples
A few from my own code. A security-header checker needs a comment so nobody later "simplifies" a failed network call into a cheerful green checkmark. A billing webhook needs a note about idempotency, because duplicate events aren't a bug. They're Tuesday. A gnarly CSS override earns one line naming the browser quirk it's papering over. And a SQL filter should explain the business rule behind the condition, not announce that, yes, a WHERE clause exists. I can see the WHERE.
Frequently asked questions
What makes a good code comment?
It answers why, never what. The code already covers the what, sitting right there in front of you. What it can't show is the intent, or the gotcha that'll bite the next person at 2am. That's the stuff worth a sentence.
Should every function have a docblock?
Nope. A tiny function with a good name and zero surprises does not need a paragraph of ceremony bolted on top. I save docblocks for the ones where the contract or some operational gotcha actually matters to whoever calls them. The rest can speak for themselves.
Are TODO comments bad?
Only the vague ones. A bare TODO fix this is a confession with no plan attached. A good one names who's on the hook and what has to happen before it can go. That's the whole difference between a reminder and graffiti.
Can comments replace tests?
Not a chance. A comment tells you what someone meant to do. A test tells you what the code actually does, right now, today. One's a story. The other's evidence. The codebases I trust lean on both, because they answer completely different questions.