Building in public from Singapore

I build free tools
that actually work

Developer tools, AI guides, crypto news, finance tips — 67+ tools, 96+ articles, all free and built to be useful.

See what I built 🧰 Try a free tool

136+

Pages

67+

Free Tools

96+

Articles

7

Sites

9

Products

🟢 Live right now

Try the demos — no sign-up

Real tools running in production on bigwinner.work. Click, use them, judge for yourself.

Code dependency graph visualization on a screen

RepoLens — X-ray any repo in one click

Paste a public repo URL, get an interactive dependency graph, blast-radius map, health grade, and security scan back in seconds. No install, no signup — live at lens.bigwinner.work.

E-commerce analytics dashboard on a laptop

AI Commerce Optimizer

An embedded Shopify app running live on a real shop — AI-driven commerce optimization you can watch working, not just read about.

Dashboard of tools and apps on a screen

bigwinner.work

The hub for everything I ship — tools, guides, prompts, and every live demo, all in one place.

Projects

What I've shipped

Free tools and resources across 7 sites, all built to be useful.

Developer workspace with code on screen

Developer Tools

ToolNest — 67+ Free Developer Tools

JSON formatter, Base64, password generator, QR codes, regex tester, color converter, JWT decoder, SQL formatter — all client-side, no signup, 100% private. Your data never leaves your browser.

AI neural network visualization

AI Tool Hub

Curated directory of the best AI tools with honest reviews and comparison guides.

Cryptocurrency trading charts on screen

Crypto Brief

Daily crypto news, Bitcoin/Ethereum/Solana guides, DeFi strategies, and market analysis.

Financial planning with charts and calculator

Finance Daily

Personal finance guides, investing strategies, budgeting tips, and side hustle ideas.

Person exercising at gym

Health Today

Workout guides, nutrition advice, mental wellness strategies, and evidence-based health tips.

Laptop and coffee, working on a side project

SideHustleStack

Curated side hustle ideas, passive income strategies, and real money-making guides.

Clean desk with notebook and coffee

Productivity Hacks

Deep work techniques, AI productivity tools, Pomodoro method, and time management strategies.

Open Source

Tools I've published

Small, dependency-free libraries and CLIs for AI agent builders — MIT licensed, free to use and fork.

jsonprism

Every angle of your JSON — graph, tree, table & two-doc diff — 100% in the browser. No account, no upload, no size paywall. Click any node for its JSONPath / pointer / jq, and copy a shareable zero-backend URL. The superior-free answer to cloud-gated JSON-graph tools.

⭐ MIT · Web · live demo

gpuroom

Will that LLM fit on your GPU? A zero-install, client-side fit calculator — quant-aware VRAM across 9 quants, KV-cache & context sliders, max-context finder, best-quant picker, multi-GPU compare, and a full/LoRA/QLoRA fine-tune memory planner. Runs entirely in the browser.

⭐ MIT · Web · live demo

cutforge-studio

Drive professional video composition, generation & editing straight from your coding agent. 135+ effect operations, an editable plan.json IR, and both an MCP server and CLI — so Claude, Codex or Cursor can cut, layer, caption and render video without you leaving the prompt.

⭐ MIT · MCP / CLI

graphscout

Cached, incremental code-graph maps so AI agents query code structure instead of reading whole files. CLI + MCP, wires into Claude Code, Codex, Gemini CLI & Cursor, with an auto-sync watch mode that keeps the graph warm as you edit.

⭐ MIT · MCP / CLI

cascade

Agent task orchestration with strategic coherence — goals & milestones on top, a pull-based agent queue below, MCP tools, and a real-time SSE dashboard. Agents claim work when ready instead of being micro-managed step by step.

⭐ MIT · Python

cronscope

The visual cron builder crontab.guru never shipped — dark-mode, a live next-run timeline in any timezone, a plain-English explainer, and one-click export to crontab, GitHub Actions, systemd timers, Kubernetes CronJobs & Hermes. 100% client-side, no server.

⭐ MIT · Web · live demo

repolens

X-ray any codebase in one command — interactive dependency graph, blast-radius, health grade, security scan & hotspot map rendered to a single HTML file. Live hosted demo at lens.bigwinner.work; on PyPI as repolens-kit.

⭐ MIT · Python · live demo

cloakpipe

Redact secrets & PII from text before it reaches an LLM API — and swap them back in the response. Reversible placeholders, 16 detectors (keys, JWTs, emails, Luhn-checked cards), zero dependencies.

⭐ MIT · Python

durablemem

Embedded, dependency-light memory layer for AI agents — SQLite + FTS5, contradiction detection, decay/pinning, and provenance. No required LLM call and no vector DB.

⭐ MIT · Python

codegraph

Cached, incremental code-graph maps so AI agents query code structure instead of reading whole files — tree-sitter AST outlines, callers/callees, deps. On PyPI as codegraph-kit.

⭐ MIT · Python

ratify

A unified contract layer for LLM agents — parameterizable contract templates enforced by deterministic checks and LLM-as-judge. 127 tests, zero heavy deps.

⭐ MIT · Python

guildhall

Assemble a guild of AI agents that self-builds a roster, self-runs a task DAG, and self-grows a memory of lessons — runs offline with zero API keys.

⭐ MIT · Python

agentic-paradigm-ladder

The Missing Abstraction Ladder — mapping 30 years of programming-language evolution to the next 10 levels of AI agent architecture.

⭐ MIT · Essay

jsonsalvage

Extract & repair JSON from messy LLM output — markdown fences, trailing commas, single quotes, unquoted keys, truncated responses. Zero dependencies.

⭐ MIT · Python

dev-prompts

120+ copy-paste AI prompts for software engineers — code review, debugging, testing, refactoring. Dependency-free CLI.

⭐ MIT · Python

mcp-wrap

Wrap any REST API into a Model Context Protocol (MCP) server in minutes — no boilerplate.

⭐ MIT · Python

mnemokit

Lightweight persistent memory for AI agents and CLI tools — SQLite + FTS5 full-text search, zero dependencies.

⭐ MIT · Python

prompt-bench

Prompt quality scorer and A/B tester for LLM prompts. Scores on 12 dimensions and flags anti-patterns.

⭐ MIT · Python

agent-loop-lite

Simplified Plan-Act-Observe loop for building AI agents — a minimal reference implementation.

⭐ MIT · Python

hermes-tool-guard

Rate-limiting and safety middleware for LLM tool calls — validates inputs, blocks dangerous patterns.

⭐ MIT · Python

context-window

Smart context window manager for LLM conversations — compresses older messages while preserving key info.

⭐ MIT · Python

videoforge

Automated short video generation engine — AI-powered scripting, voiceover, subtitles, and composition in one pipeline.

⭐ MIT · Python

agent-memory

In-memory + file-based multi-layer memory system for AI agents — no external database required.

⭐ MIT · Python

filewatch

Lightweight cross-platform file/directory change monitor for Python — zero dependencies.

⭐ MIT · Python

configkeeper

Multi-format configuration loader for Python — zero dependencies, stdlib only.

⭐ MIT · Python

shellmate

Safe shell command execution wrapper for Python — zero external dependencies.

⭐ MIT · Python

quickenv

Minimal .env loader for Python with type casting, variable expansion, and validation.

⭐ MIT · Python

texttools

Collection of text processing utilities for Python — zero dependencies, stdlib only.

⭐ MIT · Python

llm-pricing

Zero-dependency LLM API pricing table + cost estimator — turn token counts into USD for OpenAI, Anthropic, Google, Meta, DeepSeek & Mistral. Cache-aware. CLI included.

⭐ MIT · Python

hookcatch

Local webhook inspector — capture and inspect HTTP requests from Stripe, GitHub, Slack & friends. Zero dependencies, runs on 127.0.0.1, no third-party service, no payload leakage.

⭐ MIT · Python

talaria

The agent runtime that ships — typed deterministic detection + phase-gated resumable pipelines. AI writes the code; Talaria handles everything else, including SEO and traffic.

⭐ MIT · TypeScript

tokenseive

Multi-layer token optimization for LLM applications — compress prompts, map codebases, and trim output before you pay for it. Zero required dependencies.

⭐ MIT · Python

free-tools-hub

ToolNest — 67+ free online tools (JSON formatter, Base64, password generator, regex tester, QR codes & more). 100% client-side, nothing leaves your browser.

⭐ MIT · JavaScript

situroom

The zero-backend global situation room — live earthquakes, conflicts, hazards & markets on one static page. No server, no API keys, no paywall. Free local MCP server included.

⭐ MIT · JavaScript

systemsdone

AI systems, done for you — managed AI content engines & custom AI agents. Automated content pipelines, lead generation, and agent orchestration.

⭐ MIT · Python

sidehustlestack

Make Money Online — side hustles, passive income, and freelancing. Curated strategies, tools, and guides for building independent income streams.

⭐ MIT · Resources

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Tools

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The tools people use the most. All free, all private.

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{ } JSON Formatter 🔑 Password Generator 📱 QR Generator 📝 Base64 Encode 🔍 Regex Tester 🎨 Color Converter # Hash Generator 🎫 JWT Decoder 🗃️ SQL Formatter 🆔 UUID Generator ⏰ Timestamp Converter 🔗 URL Encoder 📄 Markdown to HTML 📊 Word Counter 🏠 Mortgage Calculator 📈 Compound Interest

Built by a developer
who uses his own tools

I'm Duc Nguyen, a developer in Singapore. I got tired of bloated tools that require signup, hoard your data, and bombard you with ads. So I started building my own.

Every tool runs 100% client-side — nothing is ever sent to a server. Every guide is written to actually help, not to pad SEO. Every site is free because I believe useful tools should be.

I build in public. Some things work, some don't. I ship fast, fix fast, and keep shipping.

GitHub X / Twitter

Developer workspace

Principles

How I build

🔒

Privacy first

Every tool runs entirely in your browser. Zero data collection. Zero tracking. Zero server-side processing. Your data stays yours.

⚡

Fast and lightweight

No frameworks, no bundlers, no build tools. Pure HTML, CSS, and vanilla JS. Pages load in under a second on any connection.

💎

Free forever

No paywalls, no premium tiers, no "sign up to continue." If it's useful, it should be accessible to everyone.

Start using the tools

67+ free developer tools that run in your browser. No signup, no data collection.