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.
Best Friend is the unrivaled companion app for Teenage Engineering EP-Series Samplers
$9.99 · In-app purchases
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 Best Friend for K.O. II: map the core Music 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 song library compared to competitors.
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: No offline listening options.
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: Lack of social sharing features.
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: User interface may feel outdated.
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.
Best Friend is the unrivaled companion app for Teenage Engineering EP-Series Samplers. Connect your EP-133, EP-40, or EP-1320 via USB-C to manage your hardware, upload and edit new files, and see your pad settings. Best Friend is an extended display and feature augmentation app for the physical EP-133, EP-40, or EP-1320. Connecting to one of these is REQUIRED for the app to function. Use a USB-C to USB-C cable. Lightning iPhones and iPads can connect with USB-IF certified USB-A to USB-C cable and a MFi-certified Lightning to USB adapter. Scenes: - See all notes across all banks in a Scene or Song - See fader automation lanes for each bank - Export REAL audio stems of every individual pad directly from your EP - Navigate through the Scene timeline with automatic playhead following Bounce and Export Audio Stems: - Export REAL audio stems directly from the hardware WITHOUT AI separation for any Scene or Song - Choose from every individual pads (all 48), group mixdowns, or stereo mixdowns - Fader automation is included in the export - Export MIDI data from a Scene or Song - Bring your bounces into your DAW of choice for mixing MIDI Controller: - Build rich chords with a button. Pick major, minor, suspended, or diminished triads then add a 6th, 7th, or 9th for flavour - Play the velocity-sensitive keyboard - Arpeggiator with 4 modes, 6 rates, and 3 octaves synced to the hardware clock - Configure your own custom chords to any of the Chord or Extension buttons - Split each key into 1-3 zones for playing chords in alternate positions - Add pitch bends or modulation to any chord Sample Editing: - Extract stems (drum, bass, vocal, guitar, and other instrument) from your samples - Build and edit multi-samples on the EP-1320 or EP-40 - Use Repitch to reduce the file size - Permanent cropping - Increase volume with normalize - Reverse playback - Convert stereo to mono - Change sample rate - Apply effects: 3-band EQ; compression; distortion and saturation; octaver; phaser; chorus; tremolo; delay; and reverb - Automatically detect and set the key - Save default pad settings Hardware Management: - Bulk upload samples from your Files and Videos - Bulk move, share, and delete samples - Edit and replace samples in place - Backup your Project or entire System - Import Project and System from the official EP Sample Tool - Extract Projects from your System Backups - Preview stereo mixes of your Project Backups - Save Bank Snapshots to share and recall later - Automatic iCloud syncing across your Apple devices Pads: - Mute and unmute individual pads - Apply performance effects to individual pads: mute, pitch up, pitch down, reverse - Drag and drop pads to reassign them across groups - See an entire bank of samples at once - See the sample waveform along with its name and length - See and edit the trim, attack, and release windows - See and adjust volume, pitch, pan, mute, play mode, time-stretch, and MIDI channel - See Supertone settings on your EP-40 Universal support: - works on iPhone, iPad, and MacOS with built-in iCloud syncing - works with EP-133 K.O. II, EP-40 Riddim, and EP-1320 Medieval with dedicated themes for each device Best Friend is not affiliated with Teenage Engineering in any way.
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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.