Integrated Development Environments / RAD tools / GUI-builders on Linux

General/Editors:

Amy (HTML, C,
C++, Java, SQL, LaTeX, Makefiles and many more
languages)
blIDE
(incomplete; no downloads as of yet)
IBM's Eclipse
(an extensible IDE kit; Java, C/C++, plus other languages via
plug-ins
that are becoming increasingly available, such as Perl via the
EPIC plug-in)
Code
Crusader (supports just about everything)
with the Code Medic
debugger
Glimmer
InfoDock
SGI's Jessie (doesn't
seem to exist any more)
Emediat Solutions's RadBuilder
RHIDE
CYGNUS's Source
Navigator with the Insight
debugger
SciTE
Titano
WideStudio
wxStudio

Ada:

GNAT
Programming System (GPS)
TIA (for
GNAT Ada 95)

BASIC:

TrueBASIC
(Linux version to be released soon)

C/C++:

Amy
Anjuta
ICS's BX Pro (for
Motif/C++)
Code Forge's C-Forge
Code
Blue
Metrowerks's Code
Warrior
Bloodshed Software's Dev-C++ (for
C/C++)
DiaSCE
IBM's Eclipse
(an extensible IDE kit; Java, C/C++ in late beta, other
plug-ins
pending)
gIDE
Glade
GNAT
Programming System (GPS)
CYGNUS's GNUPro
FLTK & Fluid
(for C++)
IDEntify
KDbg
KDevelop

KDE Studio
Suite 3220 Software's Moonshine and

Moonshine Professional
OpenAmulet
RHIDE
QtEZ (for
C++ w/Qt)
Scintilla
(for GTK+/C++)
Wind River Systems / TakeFive Software's SNiFF+ and SNiFF
Penguin
CYGNUS's Source
Navigator
with the Insight
debugger
TogetherSoft's Together
VisKProg
MicroEdge's Visual SlickEdit
Q Software Solutions's Wedit
VDKBuilder
VIDE (for C++
and Java)
WideStudio
wxBuilder
wxDesigner
wxStudio (for C++
and Python)
Xwpe-alpha

Objective-C:

GNUStep's ProjectCenter

ECMAScript (formerly "Javascript"):

TrollTech AS's Qt Scripter
(for the Qt Script extension of ECMAScript)
Nombas, Inc.'s ScriptEase (for
ECMAScript)

Eiffel:

Interactive Software Engineering's EiffelBench

HTML:

Java:

Amy
AnyJ (for
Java)
VioSoft Arriba
BlueJ
Chicory
Omnicore Software's CodeG
IBM's Eclipse
(an extensible IDE kit; Java, C/C++ in late beta, other
plug-ins
pending)
Elixir (for
Java, HTML, Scheme, TCL)
FreeBuilder
Ginipad
IntelliJ's IDEA
Jasmine
Borland's JBuilder aka
JavaBuilder
JCreator LE or
Pro
BulletProof's JDesignerPro
Jedi
Jedit (for Java,
when used with plug-ins)
Jipe
JJTop
JOODA
Allaire's Kawa
ProSyst's
mBedded Builder (for embedded Java)
NetBeans
Developer
Data Representations's Simplicity
and Simplicity
Professional
Wind River Systems / TakeFive Software's SNiFF+ and SNiFF
Penguin
CYGNUS's Source
Navigator with the Insight
debugger
Sun One Studio
4 (formerly Forte)
SwingSoft's SwingBuilder
TogetherSoft's Together
VIDE (for C++
and Java)
IST's Visaj
Compuware's OptimalJ
IBM's VisualAge
Java
Visual
Paradigm
IBM's WebSphere
Application Developer (for Java J2EE)

Pascal:

Alice
Pascal
Borland's "Kylix Open
Edition" (for GPL-licensed projects only, using
Object Pascal aka Delphi or C++ source code, with Java to
be added later)
Lazarus (for
Object Pascal/Delphi)
fpGUI
(for Object Pascal/Delphi)
RHIDE

Perl:

ActiveState's Komodo
PerlComposer
WideStudio
wxPerl

PHP:

ActiveState's Komodo
Nexidion
Designer
Xored Web
Studio (works as an Eclipse plug-in)
Zend
IDE
Maguma Workbench
(proprietary)
Bluefish (primarily an
HTML editor)
Quanta+ (primarily an
HTML editor
Screem (PHP, XML; primarily an
HTML editor / site-development environment)

Python:

ActiveState's
ActivePython
BlackAdder
(for Python and Ruby)
Boa-Constructor
Cooledit
Guido van Rossum's IDLE
Jext
ActiveState's Komodo
PythonWare's PythonWorks
Pro
SPE (Stani's Python Editor)
ViPEr
ViPYL
WideStudio
Archeopteryx Software's Wing IDE
wxPython
wxStudio (for C++
and Python)
Digital Creations's Zope
Studio

QT:

QtEZ (for
C++ w/Qt)
TrollTech AS's Qt Scripter
(for the Qt Script extension of ECMAScript)

Ruby:

BlackAdder
(for Python and Ruby)
WideStudio

Scheme/Lisp:

Elixir (for
Java, HTML, Scheme, TCL)
Jabberwocky
(for Lisp)

Smalltalk:

Squeak
(Smalltalk-80)
VisualAge
Smalltalk
Cincom's VisualWorks
Smalltalk

SQL:

Amy

TCL/Tk:

Elixir (for
Java, HTML, Scheme, TCL)
ActiveState's Komodo
Quick-Tk
Tcl
Developer Studio (for Tcl/Tix)
Visual Tcl

wx (cross-platform/cross-language GUI library):

Boa-Constructor
wxBuilder
wxDesigner
wxPerl
wxPython

Other:

EXOR International Inc.'s
eVGS Development Suite (not ported yet)
MetaCard Corp.'s MetaCard (for
MetaTalk)
National Instruments's LabView
Omnis
Studio (for the Omnis 4GL)
Runtime Revolution Ltd.'s Revolution (for
Transcript)

Warning: Some of the above are binary-only and
x86-Linux-only.
http://linuxmafia.com/faq/Devtools/ides.html