23 free developer tools that run in your browser — no download, no login

You need to decode a JWT. You open a new tab, search, pick the first result that doesn’t look sketchy, paste your token in, and hope the site isn’t logging it. You repeat this seven times a week for seven different tools. There’s a better way.

Traceptor’s web toolkit at traceptor.com/tools is a collection of 23 developer and QA utilities that run entirely in your browser. No account, no email, no download — just open and use. Every tool processes your data locally; nothing is sent to a server.

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Text and code utilities

JSON Formatter

Paste raw JSON and get it back pretty-printed, validated, and minified in one click. Syntax errors surface immediately with a clear message instead of an unhelpful parse failure.

Diff Checker

Paste two blocks of text and see exactly what changed, line by line. Useful for comparing API response snapshots across environments, config files before and after a deploy, or two versions of a log.

Regex Tester

Write a pattern, enter a test string, and watch matches highlight in real time. Each match shows its [offset, length]. Flags for case-insensitive and multiline matching are toggleable without editing the pattern. Invalid patterns show an error immediately.

Markdown Preview

Type or paste Markdown on the left; see the rendered HTML on the right with live updates. Copy the final HTML to the clipboard for pasting into a CMS, email template, or documentation system.

Encode / Decode

Converts text between Base64, URL encoding, HTML entities, and Hex. Paste the input and the tool auto-detects direction. Useful for debugging query strings, reading cookie values, or inspecting encoded payloads in captured HTTP traffic.

Generators

QR Generator

Create a QR code from any URL, plain text, email, phone number, or Wi-Fi credentials. Customize the foreground color, background color, and style (squares, dots, or rounded corners), then export as PNG, SVG, or JPEG. Your Wi-Fi password or internal staging URL never touches a third-party QR service.

UUID Generator

Generates UUID v4 identifiers instantly — as many as you need, copy individually or in bulk. Useful for seeding test fixtures, migrations, or any place you need a guaranteed-unique key.

Lorem Ipsum Generator

Generates placeholder text by paragraph, sentence, or word count. Paste it into wireframes, mockups, or any design that needs realistic text density without actual copy.

Password Generator

Creates strong passwords and secrets with a configurable character set (uppercase, lowercase, digits, symbols) and a live entropy meter so you can see exactly how many bits of randomness you’re getting. All randomness is generated on-device via the browser’s crypto.getRandomValues.

Mock Data Generator

Generates fake names, email addresses, phone numbers, addresses, and full JSON payloads. Set the field types and quantity, get a ready-to-paste dataset for your test suite, Postman collection, or database seed script.

Security and cryptography

Hash Generator

Paste any text and get MD5, SHA-1, SHA-256, SHA-384, and SHA-512output simultaneously. Toggle uppercase hex if your system requires it. Uses the browser’s native SubtleCrypto API for the SHA family — the same primitives your production code uses.

JWT Decoder

Splits a JWT into its header, payload, and signature, decodes each section, and formats the JSON. Expiry (exp), issued-at (iat), and not-before (nbf) timestamps are rendered as human-readable dates so you can tell at a glance whether the token is still valid.

Cert Public Key Extractor

Drop a .cerfile (DER or PEM format) and extract the raw Base64 public key in the exact format Swift’s SecKeyCopyExternalRepresentation returns. Useful when you need to pin a certificate hash in your iOS app and want to verify the key locally before hardcoding it.

Mobile and iOS tools

iOS Image Resizer

Upload a single high-resolution image and get back @1x, @2x, and @3x assets for your iOS project, resized entirely in the browser. No ImageMagick, no Sketch plugin, no cloud upload. The resized images download as a ZIP ready to drop into your Xcode asset catalog.

App Icon Generator

Upload one square image and generate all required sizes for iOS, Android, macOS, and watchOS in one pass. Output includes a Contents.json for Xcode. Optional corner-radius slider and background color picker before export.

Deep Link Tester

Build app:// deep link URLs from a scheme, host, path, and query parameters using a form UI rather than hand-editing strings. Copy the final URL or scan the generated QR code on a real device to test the link end-to-end.

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Data conversion

JSON to Swift

Paste a JSON response and generate Codable Swift structs instantly. Options include struct vs. class, access level (internal / public), CodingKeys, and optional vs. non-optional properties. Snake_case keys are converted to camelCase automatically and Swift reserved words are escaped.

CSV ↔ JSON Converter

Convert CSV to a JSON array of objects (first row becomes keys) or flatten a JSON array back to CSV. Useful for data migration scripts, import/export testing, or transforming a spreadsheet export for use in a test fixture.

Timestamp Converter

Convert between Unix timestamps and human-readable dates in both directions. Handles seconds and milliseconds. Shows UTC and your local timezone side by side so you don’t have to mental-math the offset.

Number Base Converter

Converts integers between decimal, hexadecimal, binary, and octal simultaneously. Useful when reading memory addresses, bitmasks, or HTTP status codes in raw packet captures.

URL Parser

Paste any URL and see it broken down into protocol, hostname, port, path, query parameters (as a key/value table), and fragment. Especially useful for debugging redirect chains and OAuth callback URLs where a single misplaced & breaks the flow.

Color Converter

Enter a color in any format — HEX, RGB, HSL, HSV, or CMYK — and get all the others instantly. A live preview swatch updates as you type. Useful when a design file uses HSL but your CSS needs HEX, or when matching a brand color across different tools.

Cron Builder

Build cron expressions using a visual editor (minute, hour, day, month, weekday pickers) and see a plain-English description of the schedule as you configure it. The next five run times are listed so you can confirm the expression fires when you expect before deploying.

How to access all 23 tools

All tools are available at traceptor.com/tools. No login, no account, no download required — they work in any modern browser on macOS, Windows, or Linux. Use the search bar at the top to filter by name or keyword (keyboard shortcut: ⌘K).

The toolkit is maintained alongside the Traceptor macOS app, so new tools appear in both places as they ship. If you already use Traceptor for HTTP debugging, the same tools run offline inside the Mac app with no browser tab required.