Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
Judder is the best haptic editor on iOS: a workbench for developers who want to design feedback by feel, not by guesswork
$0.99
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
A product spec, screen plans, and build steps for your coding agent.
First kit free with a verified email
Combine features and design from your favorite apps.
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Generating… usually about a minute.
What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
A product spec, phased build plan, differentiation notes, and screen references.
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Goal: Send a clear invoice after finishing a job.
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
Rork plan preview for Judder Haptics: map the core Developer Tools workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Assumption to check: Limited customization options for haptic feedback patterns
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: No option to share patterns with others
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: Lack of user feedback on patterns
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: No tutorial or onboarding for new users
Validate with people who use this workflow before building.
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Judder is the best haptic editor on iOS: a workbench for developers who want to design feedback by feel, not by guesswork. Build tactile patterns on the iPhone your users will hold, see every event on a shared timeline, and export the result as AHAP JSON or paste-ready Swift. Haptics are temporal. One event at full intensity is already the hardware maximum, so stronger feedback comes from rhythm, density, overlap, envelope and context. Most haptic feedback is one buzz. Judder builds the whole chain: transient hits, continuous beds and dense bursts on one axis, overlapping wherever you want them to. Scrub parameters, replay the pattern, and learn what changes the feel before you put it in your app. START FROM REAL MOMENTS Practical recipes for the moments an iOS app actually has: alerts, incoming calls, long press feedback, checkout success, scrubber texture, toggles and sustained physical effects. Open a pattern and adjust intensity, sharpness, duration, gaps, attack, release, burst spacing, loop behaviour and audio support, then keep the version that feels right. SEE THE WHOLE PATTERN The editor shows a haptic lane over an audio lane with a live playhead, so you can see whether a burst sits on top of a bed, whether an audio file covers the whole pattern, and where loop seams will land. A burst is not one row in a list. It is every impulse it expands into, drawn at the real spacing. Add one of the bundled beds or import your own short audio file, trim it, audition it, and use it alongside the haptic to shape the result. TAKE IT WITH YOU Copy AHAP JSON for a resource file, copy Swift for a constant in your project, or share the files out of the app. The export keeps authored structure where possible, validates the resolved timeline, and includes the audio sidecar when a custom bed needs to travel with the AHAP. KNOW YOUR HARDWARE The Engine tab reports haptic hardware support, audio-haptic support, device identity, audio-session behaviour and global playback calibration. On the Simulator, Judder is honest about what cannot be felt. On device, it is a compact lab for getting tactile feedback right before it ships. Judder is built for developers and design teams who already know haptics matter and need a better way to choose what they should feel like. No account. No backend. No network dependency. Just timeline, playback, tuning and export.
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Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.