About Swiss-Knives
Swiss-Knives is a collection of 26 small, fast utilities for developers and electrical engineers. Every one of them runs entirely in your browser: there is no backend, no account system, and nothing you type is ever transmitted anywhere.
Why it exists
Most everyday engineering tasks — decoding a token, checking a resistor value, sizing a trace — take about fifteen seconds of actual work. Finding a tool that does them without a sign-up wall, an interstitial, or a paste box that quietly uploads your data to someone's server takes considerably longer. Swiss-Knives is the answer to that: open the page, do the thing, close the tab.
The client-side-only constraint is the whole design, not a feature. It means you can paste a production JWT, an authenticator secret, or a customer's data into a tool here without that being a security incident, because there is no server for it to reach.
What is here
- Developer Tools — 13 tools. Fast, free utilities for everyday developer work — QR codes, JWTs, hashes, JSON and more. No accounts, no uploads.
- Electrical Engineering Tools — 13 tools. Fast, free calculators and references for everyday electronics — Ohm’s law, resistor codes, filters, timers and more. Everything runs in your browser.
How it is funded
The site is free and funded by display advertising. That is the only revenue source: there is no paid tier, no affiliate linking inside tool results, and no sponsored placement in the rankings or recommendations. Advertising is also the only third party involved in running the site — see the privacy page for exactly what that entails and how to decline advertising cookies.
Ads are kept out of the working area of each tool. You will not find one placed where a Copy or Download button belongs, and no tool result is ever gated behind an advertisement.
Editorial standards
Every tool page carries an explanation of the underlying method, the formulas or specifications it implements, worked examples, and the caveats that matter in practice. That material is written specifically for each tool rather than generated, and the engineering content cites the standard it follows — IPC-2221 for trace width, RFC 6238 for time-based one-time passwords, the AWG geometric definition for wire gauge, and so on.
Where a result is an estimate rather than a derivation — battery runtime, conductor ampacity — the page says so explicitly. Engineering calculators here are aids to judgement, not substitutes for the applicable code or standard, and anything safety-related should be checked against it.
How it is built
Swiss-Knives is an Angular application, prerendered to static HTML and served from a content-delivery network. Cryptographic operations use the browser's own Web Crypto API rather than a bundled implementation. The whole site works offline once loaded, and installs as a progressive web app if you want it in your dock.
Get in touch
Corrections are genuinely welcome — if a formula, a default, or a caveat here is wrong, it should be fixed. The contact page has the addresses.