Developer Utilities
undefined Built for founders, media buyers, and operators who require rapid, client-side computation with zero telemetry and zero cloud storage.
Specialized in-browser utilities
Verified deterministic math
0 KB server data transfer
No signup, paywall, or ads
Available Tools & Engines
WCAG 2.2 & APCA Color Contrast Calculator
Audit text and UI contrast ratios against W3C WCAG 2.2 Level AA/AAA and modern APCA readability psychophysics algorithms.
JSON Formatter & Validator
Format, prettify, minify, and validate JSON payloads with syntax error detection and air-gapped security.
Base64 Encoder & Decoder
Convert strings, image files, and binary buffers to and from Base64 encoding with 100% offline security.
URL Encoder & Decoder
Encode special characters into percent-encoded URI strings and decode query parameters accurately.
Unix Timestamp Converter
Convert Unix epoch timestamps (seconds and milliseconds) to human-readable dates and vice-versa in any timezone.
UUID v4 Generator
Generate cryptographically strong Version 4 UUIDs (RFC 4122) in single or batch quantities in browser.
Regex Tester & Matcher
Test regular expressions against sample strings with instant highlight, match group extraction, and flag toggling.
JWT Token Decoder
Decode JSON Web Token headers, payloads, and claims without sending private security tokens over the wire.
AI Token & LLM API Cost Calculator
Compare monthly API costs across OpenAI GPT-4o, Claude 3.5, Gemini 2.0 Flash, and DeepSeek R1 with caching.
Tailwind v3 to v4 @theme & OKLCH Migrator
Migrate legacy tailwind.config.js to Tailwind v4 CSS-first @theme directive, convert Hex/RGB palettes to high-gamut oklch(), and check breaking changes.
Why Operators Rely on the Developer Utilities Suite.
Modern digital businesses operate in high-velocity environments where margin erosion occurs in fractions of a percent. Whether managing paid media budgets across Meta and TikTok Ads, auditing multi-currency payment gateway splits across Stripe and PayPal, or preparing digital assets and confidential invoices, operators require computational precision without compromising corporate privacy.
The Developer Utilities suite on SwiftKitHub solves this challenge through an air-gapped, zero-telemetry architecture. Unlike conventional web applications that transmit sensitive transaction values, product COGS, and proprietary media files to remote cloud servers for processing, SwiftKitHub evaluates 100% of arithmetic formulas, image transformations, and document streams directly inside the client's local browser sandbox.
Every calculator in this suite executes using 64-bit IEEE 754 floating-point arithmetic in JavaScript, guaranteeing sub-16ms recalculations on every keystroke. This client-centric computing model eliminates network latency, shields merchants from server outages during peak traffic events like Black Friday / Cyber Monday, and ensures that confidential business economics never leak to third-party databases.
Additionally, all tools support stateless URL permalinks. By serializing active input states directly into the browser URL fragment and query parameters, media buyers and founders can instantly export, bookmark, and share complex financial scenarios with colleagues and agency partners without creating accounts or storing sensitive data in external databases.
Frequently Asked Questions.
Technical documentation, formula methodologies, and privacy standards for the Developer Utilities suite.
Browse All 113 Digital Utilities →What utilities are included in the Developer Suite on SwiftKitHub?
The suite features essential development tools including a JSON formatter and validator, Base64 encoder/decoder, Unix timestamp converter, URL slug generator, and cryptographically secure UUID v4 generator.
Is JSON formatting and validation executed strictly within my local browser sandbox?
Yes. Your JSON payloads, configuration files, and authentication tokens are parsed exclusively in memory using native JSON.parse and syntax formatters. Sensitive API responses are never logged or cached.
What standard is used for client-side UUID v4 generation?
UUIDs are generated using the browser's crypto.randomUUID() API, adhering to RFC 4122 version 4 standards with 122 bits of cryptographic entropy.
How does the Unix timestamp converter handle milliseconds and time zones?
It automatically detects whether an entered timestamp is in seconds (10-digit) or milliseconds (13-digit), outputting UTC, local system time, and ISO 8601 formatting with relative time calculations.
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