App Overview

Jayson icon

Jayson

Simon B. Støvring · Developer Tools

Jayson is a JSON viewer and editor for iPhone and iPad

Free · In-app purchases

PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
4.5
430 ratings · Top 15%

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.

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Build Kit

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A product spec, screen plans, and build steps for your coding agent.

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What's included19 files

A product spec, phased build plan, differentiation notes, and screen references.

  • START_HERE
  • AGENTS
  • EVIDENCE
  • SPEC
  • BUILD_PLAN
  • DIFFERENTIATION
  • skills/
  • screens/
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Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.

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.

Screen plan

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.

Differentiate and validate

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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Free quick prompt For a smaller starting point

Quick prompt

> SELECT BUILD PLATFORM:

Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.

// RORK SYSTEM PROMPT
Rork plan preview for Jayson: 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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Opportunities

AI-GENERATED OPPORTUNITY HYPOTHESES

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

Provide detailed error messages and suggestions for correction.

Assumption to check: Users report issues with JSON formatting errors not being specific enough.

Validate with people who use this workflow before building.

Hypothesis 2

Allow users to choose formatting styles and themes.

Assumption to check: Limited customization options for JSON formatting styles.

Validate with people who use this workflow before building.

Hypothesis 3

Optimize the app to handle larger JSON inputs more efficiently.

Assumption to check: Performance issues with large JSON files.

Validate with people who use this workflow before building.

Hypothesis 4

Simplify the pricing model and provide clear explanations of premium features.

Assumption to check: In-app purchases can be confusing for users.

Validate with people who use this workflow before building.

App evidence

Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.

App Store description

Jayson is a JSON viewer and editor for iPhone and iPad. Browse JSON as a structure, edit values, and save your changes back to the file. Whether you're inspecting an API response, checking a config file, or making a quick fix on the go, Jayson turns raw JSON into something you can actually read and change. BROWSE AND EDIT - Open JSON files stored on your device or in iCloud Drive. - Toggle between a structured table view and syntax highlighted text. - Add new values and keys, and save your changes back to the file. - Parse text or the contents of a URL from your clipboard into JSON. - Highlight a key from a child of an array to get a quick overview of your data. TABS, SPLITS, AND WINDOWS - Switch between files, or different objects in a single file, using tabs. - Compare JSON in a single file or across files using multiple splits. - Open multiple windows on the iPad. WORKS WITH SHORTCUTS Jayson integrates with Shortcuts, which comes in handy for debugging API calls, previewing JSON files, and building workflows around JSON. - Pass a response from Get Contents of URL to Jayson to see how it is structured. - Open JSON as a document you keep working on, or as a temporary preview. - Format JSON and hand the result to the next action, using spaces or tabs. FREE, WITH AN OPTIONAL UPGRADE Jayson's core functionality is free. Browsing, editing, saving, splits, Shortcuts, and working with up to two tabs at a time cost nothing. A one-time in-app purchase enables having more than two tabs open at once, switching between light and dark themes, and personalizing the app icon, accent color and type icons. One purchase, no subscription.

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Screenshots

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Build scope

Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.

Define the first version

Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.

Set boundaries

Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.

Check the hard parts

Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.

SUGGESTED BUILD STACK
React Native
Expo
Zustand
react-navigation
react-native-paper
Jest
BUILD KIT DIFFICULTY
Intermediate

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.