usefulweb.site: 244 focused tools that just work
Calculators, checkers, planners and technical explorers with transparent assumptions. Every tool gives people a clear page and gives AI agents the identical result as JSON, OpenAPI and MCP.
Premium apps
Full software programs, free in your browser. No sign-up, your projects stay on your device, and every engine is also available to AI agents.
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Kerfwise
Cabinet & furniture CAD
Design cabinets and furniture, get cut lists, optimised sheet layouts, costs and drawings.
- 16 parametric cabinet & furniture types incl. diagonal, L-shaped and angled corners
- Kitchen planner: snapping runs, mitred or one-piece L worktops
- Cut list + polygon-aware sheet nesting with lower bound
- CNC G-code (GRBL, LinuxCNC, Fanuc) with drilling and toolpath preview
- Costs, hardware, drawings, DXF/SVG/CSV export
- Runs in the browser, saves locally, free
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Kinetica
Robot motion studio
Simulate robot arms in your browser: kinematics, trajectories, collisions, program export.
- Jog a 6-axis arm and drag its TCP with live inverse kinematics
- PTP, LIN and CIRC moves with S-curve profiles and blending
- Collision and self-collision checks along the whole path
- URDF, CSV, G-code and KRL/RAPID-style program export
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Threadsmith
Embroidery digitizing studio
Draw or import artwork, turn it into stitches, export DST, PES, JEF or EXP files.
- Running, satin, tatami, contour and motif stitches with real underlay
- Built-in embroidery lettering (also on an arc), SVG import and bitmap auto-trace
- Thread-look preview, stitch-out simulator and density heat map
- Exports Tajima DST, Brother PES, Janome JEF and Melco EXP — every file re-read and verified
- Free, local-first: autosaves in your browser, no account
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Ohmforge
Virtual electronics workbench
Draw a circuit, switch it on, and measure it with real-feeling bench instruments.
- Schematic editor + SPICE-style simulator in the browser
- Oscilloscope, multimeter, Bode plotter, generator, bench supply and parameter sweep
- Animated current flow and burnt-out parts when you overload them
- SPICE netlist import/export with .param and .subckt, SVG/PNG/CSV/BOM exports
- Free, no login, projects stay on your device
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Twinworks
Factory digital twin & production simulation
Model a production line, simulate it and find the bottleneck — free, in your browser.
- Draw a factory, press play, watch parts flow and the bottleneck light up
- Real statistics: warm-up, replications and confidence intervals
- OEE, Little’s law, state Gantt and cost per good part out of the box
- What-if scenarios, buffer sweeps and a buffer allocation optimiser
- Runs locally, saves to your browser — no account, no upload
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Flipline
Drawing, pixel art & animation
A few drawings. A little life. Make a flipbook in your browser.
- Local drawing and frame-by-frame animation
- Onion skins, layers, transform handles and automatic inbetweens
- GIF, video, PNG sequence, sprite sheet and storyboard exports
- Pixel art, sprites and seven tools for people and AI agents
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Lumina
Photo editor & image toolkit
Bring out what you saw. A free photo studio, right in your browser.
- Edit photos on your device, with no upload
- Reversible adjustments, color mixer, looks, on-photo crop and styled text
- JPEG, PNG and WebP exports, plus editable projects
- Eighteen related tools available through API and MCP
Free tools & workflows
usefulweb.site is a collection of 244 free tools for everyday questions and technical checks: loan and savings calculators, travel and household planners, document and media converters, and checkers for websites, code and infrastructure. Each tool does one job, needs no account and works in any browser — most of them even without JavaScript.
Workflows chain several of these tools for one real-life task – moving home, checking a suspicious message or cleaning up subscriptions – and show every step with its own result.
- 244 free tools
- 21 categories
- 3 workflows
Free tools that show their work
Results come from deterministic programs, not from a chatbot: the same inputs always give the same answer. Every tool page explains its method and assumptions, names its sources and offers worked examples, and about 2,700 automated tests run before each release. Scripts and AI agents get the identical calculation through the JSON API and MCP.
The site is run by Marcel Flaig, an independent developer in Germany. Spotted a mistake? Every page has a feedback button, and corrections are fixed in the next release. About usefulweb: who runs it and how the tools are checked →
Missing a tool? Found a bug?
Every idea, bug report and piece of feedback is read and highly appreciated. It decides what we build and fix next.