Free tools
Free mobile app design tools
30 tools that each do one job properly — colour, assets, layout, typography and the iOS and Android numbers you keep looking up. Free to use with no watermarks and no usage limits. Sign up only when you want to download or copy the result.
Color & contrast
Pull palettes out of references, check them against WCAG, and pressure-test them for color-blind users before they ship in an app.
- Color Picker from ImageDrop in a screenshot or photo and pull out every colour in it, ready to paste into your app's theme.
- Contrast CheckerTest any foreground and background pair against WCAG AA and AAA, at both body and large text sizes.
- Colour Blindness SimulatorSee your screens the way users with each type of colour vision deficiency see them.
- Hex to RGB ConverterConvert between HEX, RGB, HSL and the platform formats iOS and Android expect.
Assets & export
Convert, resize, frame and package the image assets an App Store or Play Store submission actually asks for.
- WebP ConverterConvert PNG and JPEG to WebP, or WebP back out, with a quality slider and a live size comparison.
- SVG to PNG ConverterRasterise any SVG at 1x, 2x and 3x, with a transparent or solid background.
- Phone Mockup GeneratorDrop a screenshot into a realistic iPhone or Android frame and export it ready to post.
- Image to Base64Turn an image into a data URI you can paste straight into CSS, HTML or JSON.
- App Icon GeneratorUpload one square icon and get every iOS and Android size, packaged and ready to drop into your project.
- App Store Screenshot GeneratorTurn raw captures into store-ready screenshots at the exact sizes Apple and Google require.
- Splash Screen GeneratorGenerate launch screen assets at every iOS and Android size from one logo.
Layout & CSS
Generate the CSS behind the layouts, gradients, shadows and shapes you keep hand-writing for mobile screens.
- Flexbox GeneratorBuild a flex layout visually and copy the CSS, with a live preview that shows what each property does.
- CSS Grid GeneratorLay out rows, columns and gaps visually, place items on the grid, and copy the CSS.
- Gradient GeneratorBuild linear and radial CSS gradients with as many stops as you need, and copy the code.
- Box Shadow GeneratorDial in offset, blur, spread and colour with a live preview, and stack multiple shadows.
- Mesh Gradient GeneratorGenerate soft multi-point mesh gradients and export them as an image.
- Border Radius GeneratorShape each corner independently, including nested radii, and copy the CSS.
- Blob GeneratorGenerate organic blob shapes as SVG, for backgrounds, masks and decorative fills.
Mobile specs
Look up the iOS and Android numbers — screen sizes, icon sizes, safe areas, screenshot dimensions — without opening a spec PDF.
- Aspect Ratio CalculatorWork out the missing width or height for any ratio, with the common phone and store ratios one click away.
- Device Size ReferenceScreen dimensions, logical points, pixel density and safe areas for current iPhones and Android handsets.
- px to rem ConverterConvert pixels to rem, em, dp and sp against any root size, with a full scale table.
- iOS App Icon SizesEvery iOS icon dimension, what it is used for, and the scale factor behind it.
- Notch & Safe Area SimulatorPreview your screen against real notches, Dynamic Islands and home indicators.
- App Development Cost CalculatorEstimate what a mobile app costs to build, from feature scope, platforms and team rates.
- App Store Screenshot SizesRequired screenshot dimensions for the App Store and Google Play, with counts and limits.
AI generators
Get a first draft from AI: names, personas, and the written scaffolding around a mobile app.
Typography & content
Pair fonts, build a type scale, and get placeholder content that looks right at phone sizes.
Why these free tools exist
Most “free design tools” are lead-gen bait — a limited demo that stops working after two or three uses, or one that stamps a watermark across whatever you make. These 30 are not that. Every tool runs in full, as many times as you want, and the output has no watermark on it. There is no credit system and nothing to run out of.
Nearly all of them run entirely in your browser, which is why they are instant and why your screenshots never leave your device. We ask for a free account at one point only: when you download, export or copy the result. That is the whole trade — you get the tool, we get the chance to show you what floow.design does with a full screen.
They also share a bias. These are not generic web design utilities with a mobile label bolted on — they are built around the specific problems of shipping a phone app: safe area insets, adaptive icon masking, store screenshot dimensions, dp versus sp, and colour that still reads in direct sunlight.
How to use these tools together
- Pull a palette out of a reference image with the colour picker, then verify every text-on-surface pair in the contrast checker and pressure-test it in the colour blindness simulator.
- Settle typography with the font pairing tool and the type scale generator, converting sizes as you go with the px to rem converter.
- Build the layout with the flexbox and CSS grid generators, then add depth with box shadows and gradients.
- Check it against real hardware in the safe area simulator and the device size reference.
- Ship the store assets: the app icon generator, the splash screen generator and the App Store screenshot generator, checked against the required store sizes.
Frequently asked questions
- Are these mobile app design tools actually free?
- All 30 tools are free with no usage limits — no credit card, no watermarks, and no cap on how many times you run any of them. Every tool works in full without an account: you can use it and see the result. A free sign-in is only needed at the point you want to download, export or copy the output.
- Do I need an account to use them?
- Not to use them. Every tool runs and shows you a live result with no account at all. Signing up free is only required for the payoff — downloading a file, exporting an asset set, or copying generated code to your clipboard.
- Are my images and screenshots uploaded to a server?
- No, for almost every tool. The colour, image, mockup and converter tools all run entirely in your browser using the Canvas API, so your files never leave your device. Only the two AI tools — the app name and persona generators — send your text description to a server to generate a response.
- Can I use the output commercially?
- Yes. Everything these tools produce — icon sets, mockups, CSS, gradients, SVG shapes, converted images — is yours to use in commercial projects. There is no licence, no attribution requirement and no watermark on any output.
- Which tools work best together?
- Start with the colour picker to pull a palette from a reference, verify the pairs in the contrast checker, then use the type scale and font pairing tools to settle typography. When you are ready to ship, the app icon generator, splash screen generator and App Store screenshot generator produce the store assets.