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Free Tools · No Login · Client-only

Engineer's
Toolbox

Tools I built for my own workflow — now public. Each runs entirely in your browser. Nothing stored anywhere.

50 apps
8 categories
0 logins
⌕

Featured

46 tools
🗃️
ai

Fine-tuning Dataset Formatter

Convert Q&A pairs into JSONL training data for OpenAI, Axolotl, ShareGPT, and Unsloth

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📦
ai

LLM Response Unpacker

Paste any OpenAI, Anthropic, or Gemini API response and extract content, tokens, and cost

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📈
ai

Model Benchmark Comparator

Compare LLMs on context, pricing, MMLU, HumanEval, and capabilities side by side

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🔀
ai

Prompt Diff

Compare two prompt versions side-by-side — spot every change at a glance

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📏
ai

Context Window Visualizer

Paste a conversation. See exactly what fits in 8K / 32K / 128K / 200K windows — and which truncation strategy preserves the most

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🎮
ai

GPU VRAM Calculator

Estimate VRAM needed to run or fine-tune any LLM at any quantization, then see which GPUs fit

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🔧
ai

JSON Schema → LLM Tool Definition

Convert any JSON Schema or OpenAPI operation into an OpenAI / Anthropic / Google tool/function definition — the three formats differ subtly

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✂️
ai

RAG Chunk Inspector

Visualize exactly how your chunking strategy splits documents — with overlap regions highlighted and per-chunk token estimates

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🔍
ai

System Prompt Linter

Catch the silent failure modes in your system prompt — vague instructions, conflicting rules, missing output format, role drift — before they cost you tokens

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🪙
ai

Tokenizer Visualizer

See exactly how an LLM splits your text into tokens — color-coded, byte-counted, model-aware

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💰
ai

LLM Cost Calculator

Compare LLM API costs and local inference TCO side by side

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🔢
ai

Prompt Token Counter

Estimate token count and API cost for any prompt across all major models

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🎙️
ai

Voice Transcriber

Free browser speech-to-text with session history and transcript download

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📊
trading

Drawdown & Sharpe Calculator

Paste a return series and get Sharpe, Sortino, max drawdown, Calmar, and equity curve

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📉
trading

Options P&L Calculator

Visualize profit/loss at expiry across a price range for calls, puts, and spreads

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📊
trading

Position Sizer

Calculate optimal trade size with Kelly criterion and fixed-risk models

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🔌
ev

EV Charging Cost Calculator

True cost per session and per mile for any EV — accounts for time-of-use rates, solar offset, and DC fast-charging premium

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⚡
ev

Tesla Trip Cost Calculator

Calculate charging cost and time for any Tesla trip

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🌐
infra

Nginx Config Generator

Generate nginx server blocks for static sites, reverse proxies, and PHP — with SSL

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🔐
infra

SSH Config Generator

Build ~/.ssh/config host blocks from a form — ProxyJump, IdentityFile, forwarding

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🖥️
infra

Device & Browser Info

Inspect your browser, OS, hardware, network, and public IP — all displayed locally

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🐳
infra

Docker Compose Visualizer

Paste docker-compose.yml and see your service graph — dependencies, ports, volumes, networks, all rendered visually

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⚙️
infra

systemd Unit File Generator

Generate a properly-formatted systemd unit file from a command, restart policy, env vars, and user — with security-hardening defaults baked in

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🔢
dev

Base64 & URL Encoder

Encode/decode Base64, URL encoding, HTML entities, and hex — four encodings in one tool

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#️⃣
dev

Hash Generator

Generate MD5, SHA-1, SHA-256, SHA-512, and HMAC hashes from text or files

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📸
dev

Code Snippet to PNG

Turn code into beautiful shareable images with syntax highlighting and gradient backgrounds

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🎨
dev

Color Toolkit

Extract dominant colors from images and convert between HEX, RGB, HSL, and CMYK

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🖱️
dev

CSS Button Generator

Design and export custom CSS buttons with gradients, shadows, and hover effects

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📋
dev

CSV to JSON Converter

Parse CSV files or pasted text into JSON with automatic type detection and edge-case handling

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🎲
dev

Dummy Data Generator

Generate realistic fake datasets as JSON or CSV for testing and prototyping

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🌫️
dev

Glass & Mesh Gradient Generator

Generate glassmorphism panels and mesh gradients with live preview and copy-ready CSS

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🗜️
dev

Image Compressor

Compress JPEG, PNG, and WebP images client-side with target size and dimension controls

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{ }
dev

JSON Formatter & Validator

Paste raw JSON to format, colorize, validate, and minify instantly

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🔑
dev

JWT Decoder

Decode JWT header, payload, and signature — fully client-side, never transmitted

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🔐
dev

Password & Passphrase Generator

Generate cryptographically random passwords and human-readable passphrases

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⬛
dev

QR Code Generator

Generate styled QR codes for URLs, WiFi, contacts, and more — with logo embed

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⟷
dev

Text Diff / Code Compare

Compare two text blocks or code files and highlight exact additions and deletions

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⏱️
dev

Cron Expression Builder

Write, validate, and understand cron expressions with next-run previews

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📐
dev

Graphing Calculator

Basic · Scientific · 2D graph · 3D surface — all modes, zero deps

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📝
dev

Markdown Visualizer

Live Markdown editor with split preview, word count, and raw HTML export

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🔍
dev

Regex Playground

Test regular expressions against sample text with live match highlighting

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✍️
dev

Rich Text → Markdown

Paste rich text or HTML → clean Markdown, copy in one click

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🕐
dev

Unix Timestamp Converter

Unix ↔ datetime — relative time, ISO / RFC / local formats, live clock

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🏦
finance

Amortization Calculator

Monthly payment, total interest, and full amortization schedule for any loan

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💱
finance

Currency Converter

25+ currencies · USD / INR / EUR / GBP base · hardcoded rates with date

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💳
finance

Debt-to-Income Calculator

Front-end & back-end DTI — lender thresholds, max debt, income needed

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Other Tools

4 tools

Personal-utility apps I built so I wouldn't have to keep visiting other sites.

⚕️
health

BMI & Health Metrics

BMI · BMR · TDEE · ideal weight — lbs or kg, ft/in or cm

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🎲
fun

Dice Roller

Roll up to 4 dice at once with 3D animation and roll history

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🪙
fun

Coin Flipper

Single flip · multi-flip · streak tracker · probability stats

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🌍
fun

Global Clock

Live clocks in 10 timezones — CST & IST hero, 8 secondary cities

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These tools are for informational purposes only. Results are not financial, medical, or legal advice. You are solely responsible for how you use them. I am not liable for any decisions made based on these outputs.