Free digital logic tools

A small set of fast, free, in-browser tools for digital logic and computer architecture: simulate gates, generate truth tables, simplify boolean expressions, convert numbers between bases, encode text as binary, work out two's complement, and minimize a Karnaugh map. No sign-up, no install, nothing to download.

They pair with the full digiwleea course and the lab, where you build every gate from CMOS transistors and work up to a real 8-bit CPU.

Interactive simulators

Play with the real thing: build and run circuits, and drop below them to the transistor and the CPU cycle.

Logic gate simulator Build circuits from transistors and gates, flip the inputs, and watch the signals flow live. Free and online, made for students. Open the simulator → CPU simulator Watch a CPU run a real program, one step at a time: fetch, decode, execute. See the program counter, instruction register, ALU, and accumulator work together as the answer builds up. Open the simulator → Memory (latch) simulator How does a circuit remember a bit with nothing moving? Set an SR latch, release the input, and watch the bit hold itself through feedback. The origin of registers and RAM. Open the simulator → Binary addition walkthrough How does a computer add? Step through binary addition one column at a time and watch the carry ripple left, then try your own numbers. The full adder, made visible. Open the walkthrough → Binary multiplication walkthrough How does a computer multiply with no multiplication table? Shift and add: watch a shifted copy get added for each 1 bit of the multiplier, then try your own numbers. Open the walkthrough → How do logic gates work? Meet NOT, AND, OR, XOR, and NAND. Click each gate's inputs and watch the output lamp and truth table respond. The handful of rules every computer is built from. Open the walkthrough → How does binary work? Click the bits of an 8-bit number, or press +1 to count and watch the carry roll over. See that binary is just a sum of powers of two, the way every computer stores a number. Open the walkthrough → How do computers store negatives? Two's complement made clear: the top bit's place value is -128, so the number can go below zero. Toggle bits or flip the sign, and watch invert-and-add-one negate a number. Open the walkthrough → MOSFET simulator One level below the switch: drag the gate voltage on a real transistor cross-section and watch the inversion channel form and conduct. The field effect, made visible. Open the simulator →

Logic & boolean tools

Work with gates, truth tables, and boolean expressions, and minimize them.

Truth table generator Type a boolean expression with AND, OR, NOT, XOR and friends, and get the full truth table for every input combination. Open the generator → Karnaugh map solver Fill a 2, 3, or 4 variable K-map (with don't-cares) and get the minimized sum-of-products expression, grouped for you. Open the K-map solver → Boolean algebra simplifier Type a boolean expression and get its minimal sum-of-products form, computed from the truth table with Quine-McCluskey. Open the simplifier → Bitwise calculator Compute AND, OR, XOR, NOT and shifts on numbers in decimal, hex, or binary, with a per-bit breakdown that shows the logic gate behind each column. Open the calculator →

Numbers & bases

Convert, encode, and calculate across binary, decimal, hex, and more.

Binary converter Convert between binary, decimal, and hexadecimal instantly. Type in any box and the others update, with place values shown. Open the converter → Number base converter Convert between binary, octal, decimal, and hexadecimal live, plus any base from 2 to 36. Big numbers stay exact. Open the base converter → Two's complement calculator Convert decimal to two's-complement binary at 8, 16, or 32 bits and back, with the invert-and-add-1 steps and the value range. Open the calculator → Binary calculator Add, subtract, multiply, or divide binary numbers, with the result in binary, decimal, and hex, and the column-by-column carries a full adder computes. Open the calculator → Text to binary converter Turn text into 8-bit binary per character (and hex), or paste binary to decode it back to text. UTF-8 safe, both directions. Open the converter → IEEE 754 floating point converter Convert a decimal number to its 32-bit or 64-bit float bit pattern and back, with sign, exponent, and mantissa broken out. Handles zero, infinity, NaN, and subnormals. Open the converter → Gray code converter Convert a number to reflected binary Gray code and back, with the XOR derivation and a demo of consecutive values changing exactly one bit. Open the converter → ASCII table The full 128-code ASCII table with decimal, hex, octal, and binary, plus a lookup that finds any character, code, or control name like LF. Open the table →

New to this? Start with the theory: binary numbers, truth tables, the NAND gate, and Karnaugh maps. Or jump straight into the lab and build something.

How digiwleea compares

New here from another logic simulator or course? See how digiwleea is different, and why it goes all the way from a transistor to a working CPU.

Logisim CircuitVerse alternative Falstad alternative Logic.ly alternative nand2tetris online Ben Eater's 8-bit computer online Logisim online Turing Complete alternative nandgame Sebastian Lague's Digital Logic Sim

Build parts from logic gates

Step-by-step guides that build the core logic parts from gates, each with a live circuit you can toggle and open in the lab.

Build a half adder Build a full adder Build a 2:1 multiplexer Build a SR latch Build a D flip-flop