Browser-only tools, built for teams that cannot send data anywhere

Need a calculator, converter or data-handling tool that must not touch a third-party service? We build single-page tools that run entirely in the user's browser: no backend, no upload, and nothing for a compliance team to audit except the code itself.

Why This Is Fast

We maintain a library of 800+ working browser tools. Most requests turn out to be a rework of something already built and tested, so a first working version usually lands in 48 hours rather than weeks.

What You Receive

• The tool - one self-contained HTML file. It runs from a local file, from an intranet with no internet access, or from any static host.
• The source - readable and commented, with no build step and no dependencies you cannot inspect.
• A methodology note - the formulas and rules used, written so a reviewer can check a result by hand.
• A worked example - a fixed input/output pair your team can re-run to confirm the tool behaves exactly as delivered.

Engagements and Starting Prices

• Single tool - from $350, typically delivered in 3-5 working days.
• Custom logic with methodology - from $900, for rules and formulas that have to be documented and independently checkable.
• Ongoing tool work - from $1,200 per month, for teams that keep finding spreadsheet processes worth replacing.

Fixed price, agreed before any work starts. If the scope turns out to be smaller than we scoped it, the price comes down with it.

Live Example

Nothing is transmitted when our tools run: see the Data Masker, which works the same way every deliverable does.

Get in Touch

Send the input you have and the output you need, and you will get a firm quote and scope within one working day. Or email directly at [email protected].

This site is written and maintained by one person: Huang Bin, who decides what each tool does and verifies the result before it is published.

Maintained by Huang Bin · Last updated October 3, 2026