Developer Tools
JSON Editor Pro
Format, validate, compare, and explore JSON — entirely in your browser.
- Code, Tree, Table & Graph views
- Live validation & formatting
- Structural diff & merge
Powerful tools · Simpler workflows
Developer tools that make everyday work simpler.
Nivoapps is an independent studio building focused, privacy-respecting software for people who work with data and APIs — a JSON workspace that never uploads your documents, and an API client for fourteen protocols. Both free, both ready in your browser.
- Free to use
- No account required
- Private by default
- Format & validate JSON
- REST · GraphQL · SOAP
- Tree, table & graph views
- WebSocket · SSE · Socket.IO
- Structural diff & merge
- MQTT for IoT
- YAML · XML · CSV · TOML
- gRPC & PostgreSQL
- JWT decode & sign
- Code generation
- JSON Schema inference
- Local mock servers
The ecosystem
Two focused products. One way of building them.
Each Nivoapps product does one job well and lives on its own subdomain. They share the same foundations: free, account-optional, and local-first.
API Development
Voyager
A local-first API client for REST, GraphQL, WebSocket, gRPC, and 10 more protocols.
- 14 protocols in one client
- Collections, environments & history
- Import from Postman, OpenAPI, Insomnia & Thunder Client
Shared foundations
- Free to use
- No account required
- Local-first storage
- Runs in your browser
JSON Editor ProDeveloper Tools
Make sense of any JSON — without it ever leaving your browser.
The problem
Debugging JSON usually means pasting an API response, a config file, or a token into whichever website ranks first — and trusting a server you know nothing about with that data. A plain text editor is safer, but it won't tell you where the missing comma is, what changed between two payloads, or what a deeply nested structure actually looks like.
How JSON Editor Pro helps
JSON Editor Pro runs entirely client-side. It validates as you type with an exact line and column, lets you switch the same document between code, tree, table, and graph views, and bundles the diff, merge, conversion, and token tools you'd otherwise hunt down one site at a time.
- editing views
- 5
- built-in utilities
- 15
- bytes of your JSON uploaded
- 0
{ "id": "ord_2048", "status": "shipped", "total": 142.25, "customer": { "name": "Ada Lovelace", "email": "ada@example.com" }, "items": [ { "sku": "KB-01", "qty": 1, "price": 89.5 }, { "sku": "MS-02", "qty": 2, "price": 20 }, { "sku": "CB-07", "qty": 3, "price": 4.25 } ], "coupon": null}{"id":"ord_2048","status":"shipped","total":142.25,"customer":{"name":"Ada Lovelace","email":"ada@example.com"},"items":[{"sku":"KB-01","qty":1,"price":89.5},{"sku":"MS-02","qty":2,"price":20},{"sku":"CB-07","qty":3,"price":4.25}],"coupon":null}{ "id": "ord_2048", "status": "shipped" "total": 142.25, "customer": { "name": "Ada Lovelace", "email": "ada@example.com" }, "items": [ { "sku": "KB-01", "qty": 1, "price": 89.5 }, { "sku": "MS-02", "qty": 2, "price": 20 }, { "sku": "CB-07", "qty": 3, "price": 4.25 } ], "coupon": null}root {6}
- id: "ord_2048"
- status: "shipped"
- total: 142.25
customer: {2}
- name: "Ada Lovelace"
- email: "ada@example.com"
items: [3]
[0]: {3}
- sku: "KB-01"
- qty: 1
- price: 89.5
[1]: {3}
- sku: "MS-02"
- qty: 2
- price: 20
[2]: {3}
- sku: "CB-07"
- qty: 3
- price: 4.25
- coupon: null
Can't show tree — the document has a syntax error. Fix it in the Code view (or press Break it again) and the tree comes back.
| # | sku | qty | price |
|---|---|---|---|
| 0 | "KB-01" | 1 | 89.5 |
| 1 | "MS-02" | 2 | 20 |
| 2 | "CB-07" | 3 | 4.25 |
Can't show table — the document has a syntax error. Fix it in the Code view (or press Break it again) and the table comes back.
Can't show graph — the document has a syntax error. Fix it in the Code view (or press Break it again) and the graph comes back.
{
"id": "ord_2048",
"status": "shipped",
"total": 142.25,
"customer": {
"name": "Ada Lovelace",
"email": "ada@example.com"
},
"items": [
{
"sku": "KB-01",
"qty": 1,
"price": 89.5
},
{
"sku": "MS-02",
"qty": 2,
"price": 20
},
{
"sku": "CB-07",
"qty": 3,
"price": 4.25
}
],
"coupon": null
}
{"id":"ord_2048","status":"shipped","total":142.25,"customer":{"name":"Ada Lovelace","email":"ada@example.com"},"items":[{"sku":"KB-01","qty":1,"price":89.5},{"sku":"MS-02","qty":2,"price":20},{"sku":"CB-07","qty":3,"price":4.25}],"coupon":null}
{
"id": "ord_2048",
"status": "shipped"
"total": 142.25,
"customer": {
"name": "Ada Lovelace",
"email": "ada@example.com"
},
"items": [
{
"sku": "KB-01",
"qty": 1,
"price": 89.5
},
{
"sku": "MS-02",
"qty": 2,
"price": 20
},
{
"sku": "CB-07",
"qty": 3,
"price": 4.25
}
],
"coupon": null
}
Valid JSON
1 problem
Expected ',' or '}' after property value
Ln 4, Col 3
27 lines
390 B
1 line
245 B −37%
Depth 3
Spaces: 2
Minified
What you can do with JSON Editor Pro
Five ways to look at the same document
Every view edits the same underlying document, so you can read a payload as a tree, scan an array as a table, then jump back to code without copying anything.
-
Code view
The Monaco editor (the editor behind VS Code) with JSON syntax highlighting, folding, and expand/collapse all.
-
Tree view
A collapsible, virtualized tree that stays fast on deeply nested data — with search across keys and values.
-
Table view
Arrays of objects become a spreadsheet-style table, so you can scan rows instead of scrolling braces.
-
Graph view
A zoomable node graph of the document's structure, for seeing how objects and arrays nest at a glance.
-
Raw view
The plain text, exactly as it will be saved or copied.
Catch the error before your parser does
Validation runs on every keystroke using the browser's own JSON parser, and points at the exact line and column instead of a character offset.
-
Live validation
Parse errors are flagged instantly with the exact line and column.
-
Beautify
Re-indent with 2 spaces, 4 spaces, or tabs for readable, reviewable output.
-
Minify
Strip whitespace for compact, transfer-ready payloads, with a size-reduction summary.
-
Document stats
Size, depth, key counts, a breakdown by type — and duplicate-key detection, which JSON.parse silently hides.
See exactly what changed
Two responses that should match but don't? Compare them side by side, get a path-by-path change list, or merge them deliberately.
-
Side-by-side compare
Two or more documents with added, removed, and modified highlighting and synchronized scrolling.
-
Structural diff
A git-style change list by path — added, removed, moved, and modified nodes.
-
Merge
A deep, key-by-key merge where the overlay wins conflicts, and arrays either replace or concatenate.
Move between formats without a detour
Config in YAML, data in CSV, a feed in XML — convert to JSON and back, or infer a schema from a real sample.
-
YAML ↔ JSON
Convert YAML to JSON and back, preserving structure.
-
XML ↔ JSON
With attribute and namespace handling.
-
CSV ↔ JSON
With header detection and type inference.
-
TOML ↔ JSON
Convert TOML to JSON and back.
-
JSON Schema generator
Infer a JSON Schema straight from sample data, including union types for mixed arrays.
The small tools you reach for every day
The utilities that usually live in a dozen bookmarked tabs, running locally next to your JSON.
-
JWT decoder
Decode and inspect JSON Web Tokens entirely client-side.
-
JWT generator
Generate and sign test tokens with HS256, HS384, or HS512.
-
Base64
Encode and decode Base64 strings and files.
-
URL encoder
Encode and decode URL components.
-
UUID generator
Generate v4 or time-ordered v7 UUIDs in bulk.
-
Regex tester
Test regular expressions with live match highlighting.
-
Timestamp converter
Convert between Unix timestamps and human-readable dates.
-
HTTP status explorer
Look up status codes with explanations and use cases.
A workspace that remembers, on your device
Close the tab and come back tomorrow — your documents, tabs, and history are still there, stored locally in your browser.
-
Multi-tab workspace
Open, color, duplicate, and switch between several JSON documents at once.
-
Undo & version history
Auto-snapshots with a diff view, so you can step back through edits.
-
Import & export
Drag-and-drop file import; export a single document or a ZIP of every open tab.
-
Search & command palette
Search within a document, or jump to any action from a keyboard-driven palette (⌘K).
-
Works offline
Installable as a PWA; a web worker keeps large documents responsive.
-
Light, dark & system theme
Matches your OS by default, with a manual override.
Built for
Backend & frontend developers
Debugging an API response, reshaping a payload, or checking what a client actually sent.
QA & support engineers
Comparing an expected and an actual response to pinpoint the one field that differs.
DevOps & platform engineers
Cleaning up config, and converting between YAML, TOML, and JSON.
Anyone with sensitive data
Tokens, customer records, internal configs — inspected without uploading them anywhere.
Keyboard-first
- ⌘KCommand palette
- ⌘⇧BBeautify
- ⌘⇧MMinify
- ⌘⇧FSearch
- ⌘NNew tab
VoyagerAPI Development
One API client for fourteen protocols — local-first by default.
The problem
A modern backend rarely speaks just REST. Testing one often means a REST client, a separate WebSocket tool, an MQTT client, and a database console — four sets of saved requests, four places for environment variables, and an account wall on most of them.
How Voyager helps
Voyager puts every protocol behind one request builder, with shared collections, environments, history, and scripts. It works without signing up and stores your workspace locally; an optional free account adds sync, sharing, and teams.
- protocols
- 14
- import formats
- 6
- code-gen languages
- 5
Headers
- Authorization
- Bearer {{token}}
- Accept
- application/json
200 OK
{ "id": 42, "name": "Ada Lovelace", "email": "ada@example.com", "role": "admin", "active": true }
Available in: Web · VS Code
Query
query GetUser($id: ID!) {
user(id: $id) { name email }
}200 OK
{ "data": { "user": { "name": "Ada Lovelace", "email": "ada@example.com" } } }
Available in: Web · VS Code
Connected
- •System:
Connected to wss://realtime.example.com/orders - ↑Sent:
{"type":"subscribe","channel":"orders"} - ↓Received:
{"type":"ack","channel":"orders"} - ↓Received:
{"order":1042,"status":"paid"}
Available in: Web · VS Code
Streaming
- ↓Received:
{"step":"install","status":"done"}event: build · id: 17 - ↓Received:
{"step":"test","status":"passed"}event: build · id: 18 - ↓Received:
{"step":"deploy","status":"running"}event: build · id: 19
Available in: Web · VS Code
Subscribed
- •System:
Subscribed to sensors/# (QoS 1) - ↓Received:
21.4sensors/lab/temp - ↓Received:
48sensors/lab/humidity - ↑Sent:
{"fan":"on"}devices/lab/fan
Available in: Web · VS Code
Message
{ "id": "42" }
OK
{ "name": "Ada Lovelace", "plan": "PLAN_TEAM" }
Available in: VS Code extension
Fourteen protocols, honestly labelled
Request / Response
- REST / HTTPWeb · VS Code
- GraphQLWeb · VS Code
- SOAPWeb · VS Code
Streaming
- WebSocketWeb · VS Code
- Socket.IOWeb · VS Code
- Server-Sent EventsWeb · VS Code
- gRPCVS Code
IoT
- MQTTWeb · VS Code
File transfer & email
- FTP / FTPSWeb (relay) · VS Code
- SFTPWeb (relay) · VS Code
- SMTPWeb (relay) · VS Code
Raw sockets
- TCPWeb (relay) · VS Code
- UDPWeb (relay) · VS Code
Database
- PostgreSQLVS Code
What you can do with Voyager
A request builder that speaks every protocol
One interface for request/response, streaming, IoT, file transfer, email, raw sockets, and SQL.
-
Full request builder
Methods, params, headers, and bodies — raw JSON/XML/HTML/JavaScript/text with beautify, form data, or URL-encoded.
-
Authentication
Bearer token, Basic auth, API key (header or query), and OAuth 2.0 client credentials.
-
Response viewer
Pretty, raw, and preview modes; headers and parsed cookies in their own tabs, with search; status, time, and size on every response.
-
Streaming timelines
WebSocket frames, Socket.IO events, SSE messages, and MQTT topics in a live message log.
Collections, environments, and history
Structure that mirrors your API, and variables that follow you between environments.
-
Collections & nested folders
Mirror your API's resource structure, with multiple workspaces for separate projects.
-
Environments
Switch environments from the top bar and use {{variable}} substitution in URLs, headers, bodies, and protocol settings. Secret values stay hidden from viewers when shared.
-
Request history
Every request you send is logged with method, status, and timing — reopen any entry with its original configuration.
Scripts, tests, and mock servers
Prepare data before a request, assert on what comes back, and stand up an endpoint before the backend exists.
-
Pre-request scripts & tests
Plain JavaScript in a sandboxed QuickJS runtime, with pass/fail results and console output beside the response.
-
Local mock servers
Routes with path parameters, status codes, headers, bodies, and delays, plus a live request log — in the VS Code extension.
-
Code generation
Export any request as cURL, JavaScript (fetch), Node.js (axios), Python (requests), or Java (HttpClient).
Built for
Backend & API developers
Building and debugging endpoints across REST, GraphQL, and real-time protocols from one place.
Frontend developers
Exploring an API before wiring it up, and generating a ready-to-paste client snippet.
IoT & real-time teams
Watching MQTT topics, WebSocket frames, and event streams in a live timeline.
Teams leaving another client
Importing existing Postman or Insomnia collections without paying per seat to collaborate.
Keyboard-first
- ⌘↵Send request
- ⌘SSave request
- ⌘KSearch requests
- ⌘BToggle sidebar
- ⌘/All shortcuts
Find a tool
Start from the task you have.
Pick what you're trying to do and jump straight to the tool that does it — each link opens the exact page in the right product.
-
JSON Editor Pro
Format a messy JSON payload
Beautify with 2 spaces, 4 spaces, or tabs.
-
JSON Editor Pro
Find the error in broken JSON
Get the exact line and column, not a character offset.
-
JSON Editor Pro
Explore deeply nested data
Read it as a collapsible tree or a sortable table.
-
JSON Editor Pro
See what changed between two responses
A path-by-path list of added, removed, and modified values.
-
JSON Editor Pro
Merge two JSON documents
Deep merge, with a choice to replace or concatenate arrays.
-
JSON Editor Pro
Convert YAML config to JSON
And back again, preserving structure.
-
JSON Editor Pro
Turn a CSV export into JSON
With header detection and type inference.
-
JSON Editor Pro
Generate a JSON Schema
Inferred from a real sample document.
-
JSON Editor Pro
Decode a JWT
Inspect its header and claims without sending it anywhere.
-
JSON Editor Pro
Sign a test JWT
HS256, HS384, or HS512 with your own secret.
-
JSON Editor Pro
Encode or decode Base64
Strings and files, both directions.
-
JSON Editor Pro
Convert a Unix timestamp
Between epoch values and readable dates.
-
Voyager
Send a REST or GraphQL request
Right in the browser — no sign-up needed.
-
Voyager
Watch a WebSocket or SSE stream
Every frame and event in a live timeline.
-
Voyager
Subscribe to MQTT topics
Wildcards, QoS 0–2, and publishing to any topic.
-
Voyager
Mock an endpoint before the backend exists
Local mock servers in the VS Code extension.
-
Voyager
Turn a request into code
cURL, JavaScript, Node.js, Python, or Java.
-
Voyager
Import a Postman collection
Insomnia, Thunder Client, and OpenAPI work too.
-
Voyager
Share a collection with your team
Admin, Editor, and Viewer roles — free.
-
Voyager
Publish API docs from a collection
A standalone HTML page, in one click.
Why Nivoapps
Software that respects your time — and your data.
Nivoapps is an independent technology brand focused on practical, accessible, thoughtfully designed tools. The goal is simple: make everyday digital workflows simpler, and keep improving each product after launch — not just at release.
Read the story behind Nivoapps-
Private by default
JSON Editor Pro never uploads your documents. Voyager keeps your workspace on your device unless you choose to sign in. Your data isn't the product.
-
No account walls
Open either app and start working. Accounts are optional, and only ever add things like sync and sharing.
-
Free, without the fine print
No trials, paywalls, or seat limits on either product — every shipped feature is available to everyone.
-
Built around real workflows
Each product starts from a specific, repetitive task — debugging a payload, testing an endpoint — and solves it end to end instead of chasing a feature checklist.
-
Keyboard-first
Command palettes and shortcuts for the actions you repeat, with light and dark themes that follow your system.
-
Continuously improving
Products evolve through real use. In-app feedback goes straight to the person building them, not into a support queue.
Guides
Latest developer guides
Practical, in-depth write-ups on JSON, APIs, and auth — each one useful without any Nivoapps product.
The 10 JSON Syntax Errors You'll Actually Hit (and How to Fix Each One)
A practical field guide to the JSON parse errors developers run into most: trailing commas, single quotes, comments, unescaped characters, NaN, BOMs, and more — with the exact fix for each.
A Practical Introduction to JSON Schema
Learn JSON Schema by building one: types, required fields, additionalProperties, enums, arrays, $ref reuse, and the mistakes that make schemas silently accept bad data.
JSON vs YAML vs TOML vs XML: Picking a Format for Config and Data
An honest comparison of JSON, YAML, TOML, and XML — syntax, comments, type pitfalls like YAML's 'Norway problem', tooling, and which format fits configuration files versus data exchange.
FAQ
Frequently asked questions
Can't find what you're looking for? Email info@nivoapps.com — it reaches a real person.
What is Nivoapps?
Nivoapps is an independent technology brand that builds focused web applications and developer tools. This site is the central directory for everything we've shipped — each product lives on its own subdomain.
What applications are available on Nivoapps?
Two today: JSON Editor Pro, a browser-based JSON workspace, and Voyager, a local-first API client for REST, GraphQL, and a dozen other protocols. Both are listed on the Products page, and more are planned.
Are the products free?
Yes. JSON Editor Pro is completely free, with no account, subscription, or paywall. Voyager has no paid tier, no feature gating, and no seat limits — an optional free account only adds sync, sharing, and teams.
What is Voyager?
Voyager is an API development platform for building and running requests across fourteen protocols — REST, GraphQL, WebSocket, gRPC, MQTT, and more. It's available as a web app and a VS Code extension, with a desktop app in development.
Do I need to install anything to use the applications?
No. JSON Editor Pro and Voyager's web app both run entirely in your browser. JSON Editor Pro can also be installed as a PWA if you prefer an app-like experience, and Voyager has a VS Code extension — its most complete edition, with all fourteen protocols and local mock servers.
Do JSON Editor Pro and Voyager work together?
They're independent tools with no shared account or integration, but they complement each other: Voyager is for sending requests and inspecting responses, while JSON Editor Pro is for working with the JSON itself — diffing two payloads, converting formats, or inferring a schema.
Are my files or API requests stored on your servers?
No, by default. JSON Editor Pro processes and stores everything locally in your browser and never uploads your JSON to a server. Voyager is local-first — your requests, collections, and environments stay on your device unless you sign in. When you are signed in, Voyager syncs your data across your devices, and its web app can route a request through Voyager's relay when the browser can't send it directly (for example, a CORS-blocked request or an FTP, SMTP, or TCP connection). See our Privacy Policy for the full picture.
How can I suggest a feature or report a bug?
The fastest way is the in-app feedback option inside the product you're using. You can also reach us directly — see the Contact page.
How can I contact Nivoapps?
Email us at info@nivoapps.com, or use the Contact page for general inquiries, bug reports, and feedback.