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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.

69 apps
8 categories
0 logins
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Featured

65 tools
🌐
ai

Translator (EN · ES · HI)

Translate English, Spanish, and Hindi in any direction - live, in your browser, fully offline after the model loads once

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🧭
ai

Local Model Browser

Filter 54+ open-weight LLMs by hardware + task + license + capability. See which fit your VRAM at your chosen quantization, with a clearly-labeled performance estimate.

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🌳
ai

MCP / Agent Trace Visualizer

Paste a Claude Code, Cursor, Anthropic, or OpenAI trace - see the agent's tool calls as a collapsible tree with categories, results, and failure flags.

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🧪
ai

RAG Eval Toolkit

Paste a corpus + labelled queries → measure recall@K, precision@K, MRR, nDCG for BM25 (and optionally semantic) retrieval. Local, free, self-hosted alternative to RAGAS / TruLens.

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⚙️
ai

Llama.cpp / Ollama Config Builder

Pick hardware + model → get optimal CLI flags and an Ollama Modelfile. No more trial-and-error tuning.

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🧮
ai

LoRA / QLoRA Memory Calculator

Pick a base model + training mode → see peak fine-tuning VRAM and which GPUs can fit the job.

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🔌
ai

MCP Server Tester

Paste your MCP server's tools/list output, validate against the protocol spec, simulate a tool call without any LLM cost.

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🖼️
ai

Multi-modal Token Counter

Drop an image → see how many vision tokens each model charges (GPT-5, Claude 4, Gemini 2.5/3 Pro) and the cost at your usage volume.

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💾
ai

Prompt Cache Optimizer

Analyze your prompt → find the optimal cache split point → see projected monthly savings across Anthropic / OpenAI / Google / DeepSeek caching.

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🧠
ai

Reasoning Token Cost Calculator

Calculate the real cost of reasoning models — including the hidden reasoning tokens every other cost calculator ignores.

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▶️
ai

Streaming Response Player

Paste any LLM streaming log → replay it at 1× or 5×, see first-token latency, inter-token deltas, throughput.

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🎯
ai

Token Probability Visualizer

Paste a logprobs-enabled LLM response → see top-K alternative tokens at every position with their probabilities, colour-coded by uncertainty.

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⚖️
ai

Hyperscaler AI Pricing - Bedrock vs Foundry vs Vertex

Compare on-demand inference pricing for the same model across AWS Bedrock, Azure AI Foundry, and Google Vertex AI

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🗃️
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

Tesla Charge Optimizer

Time-of-use rate schedule + battery + departure → cheapest contiguous charging window.

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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

PDF Merger

Drop multiple PDFs, drag to reorder, type page ranges per file, merge to one PDF - all in your browser.

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📡
dev

WebSocket / SSE Live Tester

Connect to any WebSocket or Server-Sent Events endpoint from your browser, see frames stream live, measure latency, send messages, validate JSON inline.

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🔢
dev

Word Counter

Paste any text, see words, characters, sentences, paragraphs, reading time, reading level, and the top-10 most-used words - live as you type.

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👁️
dev

HTML Viewer

Paste HTML, see it rendered live in a sandboxed preview - resize the split, simulate phone/tablet/desktop, catch JS errors.

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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

Tax-Loss Harvest Optimizer

Paste lot-level positions, see which to sell for max harvested losses while the wash-sale rule keeps the deductions valid. Federal-only. Produces a plan - never places trades.

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🏦
finance

Amortization Calculator

Monthly + bi-weekly payment, lump-sum simulator, payoff date and full amortization schedule

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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.