Code. Run. Learn. Compete.
An intelligent online coding environment for writing, running, debugging, learning and competing, directly from your browser.
Languages
29compiled and interpreted, one editorIsolation
Sandboxed workersno network, private filesystem, hard limitsAccount
None neededrun code anonymously, rate limited per address
not saved
FlareCode. Run. Learn. Compete.
Start
Recent
Shortcuts
Ctrl + Enter
Ctrl + S
F1
Ctrl + F / H
Shift + Alt + F
Ctrl + /
Input
Output
idle
Press Execute. Your program is compiled and run in an isolated sandbox; compiler messages, stdout and stderr appear here.
Every run is recorded here with its file, language, verdict and timing.
My projects
0 projects
CollaborateShare this project live with people who sign in.
Live editingMembers edit together in the IDE; the edit key no longer counts while this is on.
Invite
People
GitHubImport a repository folder as a project, or commit and push these files.
Import into a new project
Up to 16 files and 256 KB. Dotfiles, symlinks and binary files are left out. Public repositories work without connecting.
Commit and push these files
Files are added or updated; nothing in the repository is deleted.
NewPick a language. Each language keeps its own files in this browser.
Ready
UTF-8
no language server
live
Ln 1, Col 1
Spaces: 4
How a run works
The editor never executes anything itself.01
Write
A real editor with highlighting, completion and shortcuts. Pick a language and the entry file is ready.
02
Run in isolation
The API queues the job. A separate worker compiles and executes it inside a sandbox with no network, a private filesystem, and CPU, memory, process and output limits.
03
Read the result
Compiler messages, stdout, stderr, exit code and timing come back to the editor as soon as the sandbox finishes.
Languages
Pinned toolchain versions. Adding one is a registry entry.Python3.13
JavaScript (Node.js)24
TypeScript (Node.js)24
Rust1.95
CGCC 15 (C17)
C++GCC 15 (C++20)
Java21
Kotlin2.4 (JVM 21)
Go1.25
PHP8.4
Bash5.2
Ruby3.4
Perl5.40
Lua5.4
HaskellGHC 9.6
Swift6.0
Dart3.6
Julia1.11
Elixir1.18
ErlangOTP 27
R4.4
Nim2.2
Crystal1.14
OCaml5.2
Zig0.17
Smalltalk (GNU)3.2
SQL (PostgreSQL)18
SQL (MySQL)8.4
MongoDB (mongosh)8.0