Ada Online Compiler - Run Ada Code in Your Browser

Ada is not a mainstream language. It was never meant to be. It was designed by the U.S. Department of Defense in the late 1970s for one purpose: building software where failure is not an option. Avionics. Weapons systems. Air traffic control. Railway signaling. The kind of software where a bug can cost lives.

The result is a language with an almost obsessive focus on correctness. Strong static typing, range-constrained subtypes, built-in concurrency, mandatory exception handling. Ada's compiler catches entire categories of bugs that would slip past C or C++ without a fight.

When to use an Ada online compiler

Setting up GNAT (the main Ada compiler, part of GCC) locally takes some effort. An online compiler makes more sense when you want to:

• Try Ada for the first time without committing to a full toolchain install
• Test a small procedure or package in isolation
• Experiment with Ada's type system to understand how range types and strong typing work
• Practice for embedded systems or aerospace interviews where Ada knowledge is expected
• Study concurrency using Ada's built-in tasking model

Ada code example: strong typing and tasks

This example shows two things Ada is known for -- strict type safety and built-in concurrency. It defines a constrained type for temperature readings and runs two tasks concurrently:

with Ada.Text_IO; use Ada.Text_IO;

procedure Main is

   -- Constrained type: temperature must be in range
   type Celsius is new Float range -273.15 .. 1000.0;

   type Sensor_ID is range 1 .. 100;

   -- A task type for concurrent sensor reading
   task type Sensor_Reader is
      entry Start(ID : in Sensor_ID; Temp : in Celsius);
   end Sensor_Reader;

   task body Sensor_Reader is
      My_ID   : Sensor_ID;
      Reading : Celsius;
   begin
      accept Start(ID : in Sensor_ID; Temp : in Celsius) do
         My_ID   := ID;
         Reading := Temp;
      end Start;

      Put_Line("Sensor" & Sensor_ID'Image(My_ID) &
               " reads" & Celsius'Image(Reading) & " C");

      if Reading > 100.0 then
         Put_Line("  WARNING: High temperature on sensor" &
                  Sensor_ID'Image(My_ID));
      end if;
   end Sensor_Reader;

   Reader_1 : Sensor_Reader;
   Reader_2 : Sensor_Reader;

begin
   Put_Line("Starting sensor monitoring...");

   -- Launch two concurrent tasks
   Reader_1.Start(ID => 1, Temp => 36.5);
   Reader_2.Start(ID => 2, Temp => 150.0);

   Put_Line("All sensors checked.");
end Main;

A few things stand out here. The Celsius type physically cannot hold a value below absolute zero -- the compiler enforces that. Sensor_ID is constrained to 1..100. Try to assign 101 and your program will not compile. The two Sensor_Reader tasks run concurrently using Ada's built-in tasking, no threading library needed.

This is what programming for safety-critical systems looks like. The language makes certain classes of errors structurally impossible.

Where Ada is used today

Ada is not just a historical curiosity. It is actively used in:

• Boeing and Airbus flight control systems
• European Space Agency satellite software
• Military systems across NATO countries (Ada was a DoD mandate for decades)
• Railway signaling systems in Europe
• Medical devices where software certification requires provable correctness

The Ada community is smaller than most, but the work is high-stakes. Developers in these industries tend to stay with Ada because nothing else offers the same level of compile-time safety guarantees.

Run Ada on OneCompiler

OneCompiler's Ada compiler lets you write and run Ada programs directly in your browser. No GNAT installation, no project files, no build system configuration.

It is a good starting point if you are exploring Ada's type system, practicing tasking constructs, or just want to see what a language designed for zero-failure tolerance actually feels like to write. Open the editor and try the example above.