Go Todo CLI

A small command-line to-do list manager, written to take a break from a harder project.

Overview

A CLI tool for tracking tasks — add, list, mark as done — with everything persisted to a local tasks.json file. Built as a quick side exercise while working through a harder problem elsewhere, this is a fundamentals piece rather than a system: no dependencies, one file, plain JSON storage.

Engineering Summary

The whole program is one main.go using only Go’s standard library — encoding/json, os, basic string/argument parsing. It demonstrates clean separation between the data layer (loadTasks/saveTasks) and command handling (addTask/listTasks/doneTask), and straightforward argument-based command dispatch, without reaching for a CLI framework a project this size doesn’t need.

Key Features

Add, list, and complete tasks from the command line
State persisted to tasks.json between runs
Zero external dependencies

Technical Stack

Language Go (standard library only)

Storage Local JSON file

Architecture

A single binary reads its subcommand (add, list, done) from os.Args, loads the current task list from tasks.json, applies the requested change, and writes the file back. There’s no in-memory server or long-running process — each invocation is a full load-mutate-save cycle.

graph TD
    CLI[todo command] --> Load[Load tasks.json]
    Load --> Mutate[add / list / done]
    Mutate --> Save[Save tasks.json]

Interesting Engineering Decisions

Plain JSON file over a database. For a single-user local CLI tool, a database would be pure overhead. A flat JSON file is human-readable, trivially portable, and sufficient for the actual scale of the problem — the kind of proportionate choice that matters more as projects get bigger, practiced here on something small.

Missing-file treated as an empty list, not an error. loadTasks explicitly checks os.IsNotExist and returns an empty task list rather than failing, so the first add on a fresh checkout works without requiring the user to create tasks.json by hand first.

Lessons Learned

This was a small, low-stakes way to reinforce Go basics — file I/O, JSON marshaling, argument parsing — without the pressure of a bigger project’s design decisions. Sometimes stepping away to build something this size is a faster way through a harder problem than staring at it directly.

Technologies Demonstrated

Go standard library file and JSON handling
CLI argument parsing and command dispatch
Basic data persistence patterns

Suitable Portfolio Categories

Labs · Backend Engineering · Open Source