About RedBison
Updated
RedBison is a set of 564 free tools that run in your web browser: formatters and converters for developers, file and image utilities, calculators for money, health, maths and engineering, and AI helpers for writing prompts, sizing models and setting up MCP servers. Alongside them are 386 guides that explain the formats, formulas and standards the tools rely on. There is no account to create and no paywall.
Who it is for
People who need a specific job done quickly and want to trust the answer: a developer checking a JWT or a cron expression, an engineer sizing a beam or a cable, a student checking a statistics result, an office manager converting a PDF, or a nurse drafting a patient handout with an AI assistant. Each tool page says what the tool does, how to use it, where its limits are and what to check in its output.
How a tool is built
Anything with real maths or parsing lives in its own module with focused tests, so the page and the tests run the same code. When a bug is found, a test that reproduces it is written before the fix. Where a standard already has a well-tested library (UUIDs, CSV, YAML, cron, QR codes, hashing, Protocol Buffers), the tool uses it instead of a hand-written parser.
Tools run in your browser. What you paste or upload is processed on your device, and the few tools that need the network, such as one that reads a video title from YouTube, say so on the page.
How write-ups and guides are checked
Every tool page carries a write-up with an introduction, steps, worked examples, use cases, limits and an FAQ. An automated checklist runs against every page and flags it when a section is missing, when two pages overlap too much, when an FAQ question is repeated elsewhere on the site, or when the copy falls back on stock filler phrases. Guides must be long enough to teach the topic properly and include at least one diagram.
Facts are checked against primary sources: standards bodies, RFCs and official documentation. Figures that change, such as AI model prices or the names of AI crawlers, are shown with the date they were checked. The AI prompt kits for professions are drafting aids. They do not replace medical, legal, financial or engineering judgement, and each kit lists what to review before you use a draft.
What the dates mean
The "Updated" date on a tool, guide or category page is the last time that page's own content changed: its write-up, its guide text or the tool itself. Rebuilding the site or changing a shared layout does not move it, so the date tells you something real about the page you are reading.
Found a mistake?
Email team@redbison.dev with the page and what looks wrong, or use the feedback icon in the footer of any page. Confirmed errors are fixed, and the page's Updated date moves with the fix.
Privacy and AI access
The site uses analytics to count page views and which tools get used; the privacy policy has the details. AI assistants can use many RedBison tools directly over the Model Context Protocol, and answer engines can read the catalog from llms.txt; see AI and MCP access.