Small tools for backend work.
Paste anything below and BackendBench works out what it is and checks it instantly. Plus 141 tiny tools for backend and Java developers. Nothing is uploaded unless you turn on the optional AI mode in Unravel.
Runs on your device, nothing is uploaded. Ctrl+Enter opens the best tool, Esc clears.
Paste-anything doctor Verify what an AI wrote Spring config doctor Kubernetes doctor
โญ Your favorites
Nothing starred yet. Tap the โ on any tool below and it will wait for you here, saved only in this browser.
๐ Pick up where you left off
๐ฅ Trending
A hand-picked shortlist of what backend developers reach for most.
๐ Understand Java code, don't just paste it
Paste a Kafka consumer, a Spring service or a concurrent job. Unravel teaches the concepts first, then draws the flow and walks through it step by step. The explanations use no AI by default, and nothing is uploaded unless you turn on the optional AI mode.
๐ A place to get better, not just faster
267 Java concepts, learning paths, a library of Java exceptions, cron guides, a daily quiz and cheat sheets, all in one hub.
๐ Spot the bug, watch Kafka rebalance, see N+1 happen
A new Java bug puzzle every day with a streak, plus animated playgrounds for Kafka consumer groups, JPA N+1 queries, deadlocks, garbage collection and the Spring request lifecycle. Every tool result can be shared as a link that stores nothing on a server.
Browse by category
Pick a category, then a sub-category, then the tool.
That looks like a lot. Breathe. ๐ซง
Don't be overwhelmed. Every tool lives on its own page, so when you search for exactly what you need, you land on that use case directly. Press / anywhere, type what you are trying to do, and skip the rest of the shelf.
Why use a small tool when you could ask AI?
Fair question. AI is wonderful for open-ended thinking, and we use it too. But for a job like "turn this YAML into JSON" or "when does this cron fire next", a tiny tool has a few quiet superpowers.
Instant
No queue, no spinner, no waiting for a model to finish typing. You paste, it answers while you blink.
Private by design
Your stack trace, token or customer payload stays in the tab by default. The tools have nothing to upload, and the only feature that can send code is the optional AI mode, which is off until you turn it on.
Same answer, every time
Deterministic means the same input always gives the same output. No "regenerate", no vibes, no surprise creativity.
No hallucinated syntax
A model may confidently invent a seven-field cron that your scheduler rejects. These tools run the real rules and show you the next fire times as proof.
Free, and stays free
No tokens to buy, no usage cap, no account, no subscription. Open it a thousand times a day.
Works offline
Once a page is loaded, it keeps working on a train, on a plane or behind a strict firewall.
No prompt writing
No "act as a senior engineer and please only output JSON". You get a form, a box and a result.
The honest summary: use AI to think, use a small tool to finish. Small things make a big difference: a stack trace that finally reads clearly, a schedule you can trust, ten seconds saved a hundred times a week. And yes, they are genuinely fun to poke at. ๐งช