Python projects for beginners: 14 ideas, each with a plan and what it teaches

01 Number guessing game

The computer picks a number from 1 to 100, you guess, and it says higher or lower until you get it.

Modules

random

Teaches

while loops, if and elif, converting text to numbers, catching ValueError.

First version

One round, a count of tries, and a message when you win.

Stretch goal

Swap roles: you pick a number and the computer guesses it by halving the range each time.

Time

2 to 3 hours.

The mistake is trusting input(). Type “abc” and int() raises ValueError and the program dies. Wrap the conversion in try and except and ask again. The stretch goal is the first algorithm worth knowing: halving the range finds any number from 1 to 100 in at most 7 guesses, because 2 to the power of 7 is 128.

import random

def play(low=1, high=100):
    secret = random.randint(low, high)
    tries = 0
    while True:
        raw = input(f'Guess a number from {low} to {high}: ')
        try:
            guess = int(raw)
        except ValueError:
            print('Type a whole number.')
            continue
        tries += 1
        if guess < secret:
            print('Higher.')
        elif guess > secret:
            print('Lower.')
        else:
            print(f'Got it in {tries} tries.')
            return tries

if __name__ == '__main__':
    play()

02 Password generator and strength checker

A command that creates a random password of the length you choose and rates one you type.

Modules

secrets, string

Teaches

String building, choosing at random safely, simple scoring rules.

First version

Generate 16 characters from letters, digits and a few symbols; rate by length and character types.

Stretch goal

Refuse any password found in a list of common passwords that you keep in a local file.

Time

3 to 5 hours.

Use secrets, not random, for anything that guards an account. The documentation for random says it is not suitable for security purposes, because its output can be predicted. Do the math you can show: 16 characters drawn from 71 symbols is about 98 bits of randomness, which is the length times log2(71). Print that number next to the password.

03 Word frequency counter

Read a text file and print its twenty most common words with counts.

Modules

pathlib, re, collections

Teaches

Reading files, regular expressions, Counter, sorting.

First version

Lowercase the text, split it into words, count and print the top 20.

Stretch goal

Ignore common words like “the”, count two-word phrases, print a bar chart made of # characters.

Time

2 to 4 hours.

Run it on a long public-domain book from Project Gutenberg. Two things go wrong at once: curly apostrophes split “don’t” into two words, and files saved in another encoding raise UnicodeDecodeError. Decide how to treat both and write it in the README.

import re
from collections import Counter
from pathlib import Path

def top_words(path, n=20):
    text = Path(path).read_text(encoding='utf-8').lower()
    words = re.findall(r"[a-z']+", text)
    return Counter(words).most_common(n)

04 Command-line to-do list

A program you run as todo.py add, list, done and remove, which keeps its tasks in a file between runs.

Modules

argparse, json, pathlib

Teaches

Command-line arguments, saving and loading data, functions that do one job.

First version

Four commands, tasks in a tasks.json file next to the script.

Stretch goal

Due dates, a list --overdue option, colored output with ANSI codes.

Time

4 to 6 hours.

Three cases break most first versions: the file does not exist on the first run, the file contains broken JSON after a crash, and task numbers shift after a deletion. Give each task a permanent ID that is never reused, and write to a temporary file and rename it so a crash cannot leave half a file.

python todo.py add "Buy milk"
python todo.py add "Call the dentist" --due 2026-11-05
python todo.py list
python todo.py done 1
python todo.py remove 2

05 Expense tracker from a bank CSV

Read the CSV export from your bank and print what you spent in each category this month.

Modules

csv, decimal, collections

Teaches

Parsing real-world files, exact money arithmetic, grouping data.

First version

Rows of date, description and amount; a keyword table (“tesco” is groceries) assigns categories; print totals.

Stretch goal

Find recurring charges: the same description about 30 days apart.

Time

5 to 8 hours.

Never use float for money. 0.1 + 0.2 is not 0.3 in floating point, and Decimal fixes that. Bank files also vary: some write expenses as negative numbers, some use a separate debit column, and date formats differ. Put your real file in .gitignore so it never reaches a public repository. The recurring-charge stretch goal is the same problem as the subscription graveyard idea posted on the board.

Read “Expense tracker from a bank CSV” on the board and copy its build prompt →

06 Downloads folder organizer

A script that sorts files in a folder into subfolders by type, with a dry-run mode that shows what it would do.

Modules

pathlib, shutil

Teaches

Working with the file system, dry runs, never destroying data.

First version

Map extensions to folder names (.pdf to Documents, .jpg to Images) and move each file.

Stretch goal

Write a log of every move so an undo command can reverse the last run.

Time

4 to 6 hours.

Build --dry-run first and make it the default. If a file with the same name already exists in the target folder, add a number to the new name instead of overwriting. Test on a copy of a messy folder, never on the real one. These two habits, preview first and never overwrite, are what separate a script you trust from one you fear.

07 Quiz game from a question file

A multiple-choice quiz that loads its questions from a JSON file, asks them in random order and reports a score.

Modules

json, random

Teaches

Keeping data out of code, lists of dictionaries, validating a file you did not write.

First version

questions.json with a question, four choices and the right answer; ten questions asked in random order; a final score.

Stretch goal

A 15-second timer per question, and a review of the questions you missed.

Time

3 to 5 hours.

Write the file format first, with three example questions, before any code. Then add a check that fails loudly if a question is missing its answer or the answer is not among the choices. Anyone, including you in a month, can then add questions without touching Python.

08 Hangman

A word game with six lives, where the word is shown as underscores and fills in as you guess letters.

Modules

random

Teaches

Sets, program state, writing a small function for each rule.

First version

A list of 20 words, a mask function, six lives, a win and a lose message.

Stretch goal

Read words from a file, add difficulty by word length, draw the gallows in ASCII art.

Time

3 to 5 hours.

Keep guessed letters in a set so a repeated guess costs nothing and is easy to detect. Write mask(word, guessed) as its own function and test it: mask('python', {'p', 'o'}) should give 'p _ _ _ o _'. Handle uppercase input and anything that is not a single letter before it reaches the game logic.

01 Weather lookup

Type a city and the program prints today’s high, low and chance of rain from a public weather service.

Modules

urllib.request or the requests package, json

Teaches

HTTP requests, JSON, timeouts, handling network failure.

First version

Look up a city’s coordinates, request the forecast, print three lines.

Stretch goal

Cache each answer in a file for 30 minutes and add a --units option.

Time

5 to 8 hours.

The Open-Meteo service describes its API as needing no authentication for non-commercial use, which makes it a good first API: no account and no key to leak. Always set a timeout, and print a clear message when the city is not found or the network is down. Do not paste an API key into code for any service that needs one; read it from an environment variable.

02 Caesar and Vigenere cipher tool

Encode and decode text with a shifting alphabet, then break a Caesar cipher by trying all 26 shifts.

Modules

unittest

Teaches

ord and chr, the modulo operator, test cases with known answers.

First version

caesar(text, shift) and its inverse, keeping spaces and punctuation as they are.

Stretch goal

Vigenere with a keyword, and an automatic Caesar cracker that scores each shift by English letter frequency.

Time

3 to 5 hours.

You get known answers to test against. A Caesar shift of 3 turns HELLO into KHOOR. The classic Vigenere example turns ATTACKATDAWN with the key LEMON into LXFOPVEFRNHR. Put both in your tests on day one. These ciphers are toys that anyone can break. Never use them to protect anything real.

03 Contact book with SQLite

A command-line address book that stores people in a database file and searches by name.

Modules

sqlite3

Teaches

SQL basics, tables and constraints, parameterized queries, transactions.

First version

Add, list, search and delete contacts in contacts.db.

Stretch goal

Import from a CSV, export to a CSV, reject duplicate emails with a UNIQUE constraint.

Time

5 to 8 hours.

Pass values to the database with ? placeholders and never build the SQL string with an f-string. That single habit prevents SQL injection, one of the most common ways real applications get broken into. Using the connection as a context manager commits on success and rolls back on an error.

import sqlite3

conn = sqlite3.connect('contacts.db')
conn.execute(
    'CREATE TABLE IF NOT EXISTS contacts ('
    'id INTEGER PRIMARY KEY, name TEXT NOT NULL, email TEXT UNIQUE)'
)

def add(name, email):
    with conn:
        conn.execute('INSERT INTO contacts (name, email) VALUES (?, ?)', (name, email))

04 Dice roller that understands expressions

Type 2d6+3 or 4d8-1 and get the rolls and the total, the way tabletop games write dice.

Modules

re, random

Teaches

Regular expression groups, input validation, testing randomness with a fixed seed.

First version

Parse a count, a number of sides and an optional plus or minus; print each die and the sum.

Stretch goal

Support “4d6 drop lowest”, then roll 100,000 times to check that 2d6 averages 7.

Time

4 to 6 hours.

Random programs are hard to test until you call random.seed(1) at the start of a test, which makes every run repeat. Reject nonsense such as 0d6, 1000000d6 or d. Limit the dice count so a typo does not freeze the terminal.

05 Text adventure from a data file

A small game where you type go north, take key or look, with the rooms, exits and items stored in a JSON file.

Modules

json

Teaches

Nested dictionaries, game state, parsing commands, separating a game engine from its content.

First version

Five rooms, exits between them, one item, one way to win.

Stretch goal

Save and load games, a locked door that needs the key, a second ending.

Time

6 to 10 hours.

The engine should know nothing about this particular story. If you can swap in a different JSON file and play a different game without touching the Python, you have designed it well. Write the map on paper first and check that every exit has a matching way back.

06 Flashcards with Leitner boxes

A flashcard drill where cards you get right move to a box you see less often, and cards you miss go back to box one.

Modules

datetime, dataclasses, json

Teaches

Dates, a data class, saving state, a rule that depends on the calendar.

First version

Three boxes: box 1 is due every day, box 2 every third day, box 3 every week. A right answer promotes a card, a wrong one resets it.

Stretch goal

Import cards from a CSV, show streaks and the number due tomorrow.

Time

6 to 10 hours.

Store the date each card is next due, not how many days since you saw it, and compare with date.today(). Tests can then pass in a fake today. A later extension is generating the cards: an idea on the board asks to turn the tab you have open into three questions tomorrow, which would feed a drill like this one.

Read “Flashcards with Leitner boxes” on the board and copy its build prompt →