Methodology

Everything runs in your browser

Every tool on Studio Tools is a small program that runs locally, in your own browser tab. We deliberately build it this way. Your input is not sent to a server, is not stored, and is not used for anything else. This is why the file tools say "load" instead of "upload": nothing really gets uploaded. What makes the tools fast and private is the same property: the work happens where you are.

Open-source libraries

Only a few tasks need an established library, and we only load one on the tool page that actually uses it. We keep the exact versions we deploy, together with their open-source licences, on the licences page. Your tool inputs stay local and never leave your browser. A few open-source libraries are, however, delivered from public CDNs (e.g. cdnjs, unpkg, jsDelivr); neither your inputs nor computation results are transmitted to third parties.

Calculators and their sources

Where a tool makes a financial or legal calculation, we name the parameters we use and the source behind them. The salary calculator, for example, states the tax year and the contribution-assessment ceilings in effect, and links its review date. Rates, ceilings and deadlines change, so each regulated tool shows a "Stand:" date and we track them in an open changelog so you can see when we last reviewed the values.

Testing and honesty about limits

Each calculator is checked against known example values, and the formulas that are easy to get wrong (tax brackets, checksums, date edge cases) get explicit test vectors during development. Where a tool only approximates, or only makes sense for one country or a specific input quality, the tool itself says so. A scan-based tool tells you it expects printed text, a German-calculator tool tells you it assumes German rules. We would rather warn than mislead.

Versioning and changelog

The maintenance of the tools follows a rotation: calculations and legal or rate-based parameters are versioned with a Stand: date and re-checked when inputs or regulations change. An open changelog documents when which values were last reviewed, so you can see at a glance which version stands behind each tool.

Studio Tools by Studio Chop Digital, Bremen. Have a suggestion about how a tool is built or tested? Use the contact form.