Kio's ZASM -
cli version of zasm, where you can assemble files online.
Sarcasm Z80 assembler,
by Richard Cooper. Works with any Operating System that has Perl.
KAsm z80 assember for Java.
KAsm is open source cross assembler for Z80 and 8051 family of microcontrollers written in Java. It can be run on any machine supporting Java 1.5 or later. It is available under GPL license.
SjASM, for Windows32 and Linux, including sources.
SjASMPlus - shares some code with the one above but is very different on some aspects.
Z80 ASM by Joe Moore.
AS8080 ( Version 2.0.2) & Disassembler (version 1.0.5)
This is the new version (v 2.0.2) of the 8080\z80\z180 Assembler and
8080/Z80/Z180 Disassembler (v 1.0.5) package for windows... The
Assembler supports Intel/TDL mneomonics, and is very compatible with DR
ASM and DR MAC. It also supports many synmantics from various other
assemblers, such as ASEMBL-Z . It can assemble much source with little or
no modifications. The Disassembler is full featured and contains tools to
search for data areas, and can produce assembler ready source code. It
can produce either Intel/TDL mnemonics or Zilog mnemonics. Included in
this package are support programs that were originally used to bootstrap
an S100-bus system. All are intended for hobbyist use.
Here is some sample code for it: sampz80.zip.
Kio's ZASM
Command line z80 assembler for Linux, BSD, OS X and,
hopefully, any Unix-like OS.
Supports the plain vanilla z80 stuff plus some ZX Spectrum
specific file formats.
Supports binary output and intel hex file.
Embedded Pascal Compiler Package (Shareware)
This first release provides compiler, assembler, linker and
simulator for Z80 and Z180.
Targeted for stand-alone applications (i.e. no operating system),
it allows you to use Borland's Delphi to design your
embedded application under Windows 95, or you can use it on its own.
Z80Sim
A Zilog Z80 simulator, debugger and profiler tailored for ZX
Spectrum development (but generic enough to be used with other
platforms), OS portable.