Comparison of assemblers

This is a list of assemblers: computer programs that translate ("assemble") assembly language source code into binary programs.

As part of a compiler suite

GNU Assembler (gas): GPL: many target instruction sets including ARM architecture, Atmel AVR, x86, Freescale 68HC11, Freescale v4e, Motorola 680x0, MIPS, PowerPC, IBM System z, TI MSP430, Zilog Z80.
ASxxxx Cross Assembler (part of the Small Device C Compiler project): GPL: several target instruction sets including Intel 8051, Zilog Z80, Freescale 68HC08, PIC microcontroller.
The Amsterdam Compiler Kit (ACK) targets many architectures of the 1980s, including 6502, 6800, 680x0, ARM, x86, Zilog Z80 and Z8000.
LLVM targets many platforms, however there's no per-target assembly language, instead more high-level typed intermediate representation assembly-like language used.
Some others self-hosted native-targeted language implemetations (like Golang, Free Pascal, SBCL) have their own assemblers with multiple targets. They may be used for inline assembly inside language, or even included as a library, but not always suitable for standalone application - there's no command-line tool, or only intermediate representation used as a source, or support for targets very limited.

Single target assemblers

6502 assemblers

Assembler	License	Instruction set	Host platform
64tass	GPL	MOS Technology 6502, WDC 65C02, WDC 65816/65802	various
ACME	GPL	MOS Technology 6502, WDC 65C02, WDC 65816/65802	various
AS65	Proprietary	MOS Technology 6502, WDC 65C02, WDC 65816/65802	various
ASM6	Public domain	MOS Technology 6502	various
ATASM	GPL	MOS Technology 6502	various
Atari Assembler Editor	Proprietary	MOS Technology 6502	Atari 8-bit family
Atari Macro Assembler	Proprietary	MOS Technology 6502	Atari 8-bit family
C64List	Proprietary	MOS Technology 6502	Commodore 64
CA65	GPL	MOS Technology 6502, WDC 65C02, WDC 65816/65802	various
dasm	GPL	MOS Technology 6502, others	various
dreamass	GPL	MOS Technology 6502, WDC 65816/65802	various
French Silk	Proprietary	MOS Technology 6502	Commodore 64
Kick Assembler	Proprietary	MOS Technology 6502	various
Lisa	Proprietary	MOS Technology 6502	Apple II series
MAC/65	Proprietary	MOS Technology 6502, WDC 65C02	Atari 8-bit family
Macross	MIT License	MOS Technology 6502	various
MADS	Public domain	MOS Technology 6502, WDC 65816/65802	various
MAE	Unknown	MOS Technology 6502, WDC 65C02, WDC 65816/65802	Atari 8-bit family
Magic ASM	unknown	HuC6280	MS-DOS
Merlin	Proprietary	MOS Technology 6502, WDC 65C02, WDC 65816/65802	Apple II series, Commodore 64, Commodore 128
MOSASM	GPL	MOS Technology 6502	various
NESASM	unknown	Ricoh 2A03	MS-DOS
Ophis	MIT License	MOS Technology 6502, WDC 65C02, MOS Technology 4502/4510 (experimental)	various
ORCA/M	Proprietary	MOS Technology 6502, WDC 65C02	Apple II series
S-C Assembler II	Proprietary	MOS Technology 6502	Apple II
TMPx	Proprietary	MOS Technology 6502	various
vasm	Free	MOS Technology 6502	various
VISUAL6502	GPL	MOS Technology 6502	various
WLA DX	GPL	MOS Technology 6502, others	various
XA65	GPL	MOS Technology 6502, others	various
XASM	Public domain	MOS Technology 6502	various

680x0 assemblers

Assembler	Open source	License	Instruction set	Host platform	Active development
A68K	No	Free	Motorola 680x0	Commodore Amiga	No
ASM-One Macro Assembler	No	Free	Motorola 680x0	Commodore Amiga	No
Digital Research Assembler	No	Proprietary	Motorola 680x0	Atari ST	No
Fantasm	No	Proprietary	Motorola 680x0	Apple Macintosh	No
GFA-Assembler	No	Proprietary	Motorola 680x0	Atari ST	No
GST Macro Assembler	No	Proprietary	Motorola 680x0	Atari ST	No
HiSoft DevPac Assembler	No	Proprietary	Motorola 680x0	Commodore Amiga, Atari ST	No
Mac Assembler	No	Proprietary	Motorola 680x0	Apple Macintosh	No
MaxonASM	No	Proprietary	Motorola 680x0	Commodore Amiga	No
Metacomco Macro Assembler	No	Proprietary	Motorola 680x0	Commodore Amiga, Atari ST	No
MPW Assembler	No	Proprietary	Motorola 680x0	Apple Macintosh	No
OMA	No	Proprietary	Motorola 680x0	Commodore Amiga	No
PhxAss	No	Free	Motorola 680x0	Commodore Amiga	No
Pure Assembler	No	Proprietary	Motorola 680x0	Atari ST	No
Data Becker Profimat	No	Proprietary	Motorola 680x0	Atari ST	No
Seka Assembler	No	Proprietary	Motorola 680x0	Commodore Amiga, Atari ST	No
TurboAss	No	Free	Motorola 680x0	Atari ST	No
vasm	Yes	Free	Motorola 680x0	various	Yes

ARM assemblers

Assembler	License	Instruction set	Host platform
Archimedes Assembler	Proprietary	ARM	Acorn Archimedes
ARM, inc. armasm	Proprietary	ARM	Linux, Windows
FASMARM	Free	ARM	various
IAR ARM Assembler	Proprietary	ARM	Windows
Microsoft armasm	Proprietary	ARM	Visual Studio 2005
vasm	Free	ARM	various

IBM mainframe assemblers

Assembler	License	Instruction set	Host platform
BAL	Free	IBM System/360	IBM BPS/360
Dignus Systems/ASM	Proprietary	z/Architecture	numerous
HLASM	Proprietary	z/Architecture	numerous
IBM Assembler D	Free	IBM System/360	IBM DOS/360
IBM Assembler F	Free	IBM System/360	IBM OS/360 and CP-67/CMS
IBM Assembler H	Proprietary	IBM System/360 and System/370	IBM OS/360 and successors
IBM Assembler XF	Free	IBM System/370	numerous
PL360	Free	IBM System/360	IBM OS/360

Power Architecture assemblers

Assembler	License	Instruction set	Host platform
IBM AIX assembler	Proprietary	POWER	IBM AIX
MPW Power Assembler	Proprietary	PowerPC	Apple Power Macintosh
Power Fantasm	Proprietary	PowerPC	Apple Power Macintosh
StormPowerASM	Proprietary	PowerPC	PowerPC Amiga
vasm	Free	PowerPC	various

x86 assemblers

Assembler	Operating system	Open source	License	x86-64	Active development
A86/A386	Windows, DOS	No	Proprietary	No	No
ACK	Linux, Minix, Unix-like	Yes	BSD since 2003	No	1985-? ^[1]
Arrowsoft Assembler	DOS	No	Public Domain	No	No
IBM ALP	OS/2	No	Proprietary	No	No
AT&T	Unix System V	No	Proprietary	No	1985-?^[2]
Bruce D. Evans' as86	Minix 1.x, 16-bit part in Linux	Yes	GPL	No	1988-2001^[3]
Digital Research ASM86	CP/M-86, DOS, Intel's ISIS and iRMX	No	Proprietary	No	1978-1992
DevelSoftware Assembler	Windows, Linux, Unix-like	No	Free	Listed, N/A	No
FASM	Windows, DOS, Linux, Unix-like	Yes	BSD with added Copyleft	Yes	Yes
GAS	Unix-like, Windows, DOS, OS/2	Yes	GPL	Yes	Since 1987
GoAsm	Windows	No	Free	Yes	Yes
HLA	Windows, Linux, FreeBSD, OS X	Yes	Public domain	No	Yes
HJWASM/JWASM/WASM	Windows, DOS, Linux, FreeBSD, OS/2	Yes	Sybase Open Watcom Public License	Yes	Yes
LZASM	Windows, DOS	No	Free	No	No
MASM	Windows, DOS, OS/2	No	Microsoft EULA	Yes	Since 1981^[4]
Mical a86	Unix, DOS, PC/IX	Yes	?	No	1982-1984^[5]
NASM	Windows, Linux, OS X, DOS, OS/2	Yes	BSD	Yes	Yes
Tim Paterson's ASM	86-DOS, DOS DEBUG	No	Proprietary	No	1979-1983
POASM	Windows, Windows Mobile	No	Free	Yes	Yes
RosAsm	Windows	Yes	GPL	No	No^[6]
SLR's OPTASM	DOS	No	Proprietary	No	No
TASM	Windows, DOS	No	Proprietary	No	?^[7]^[8]
TCCASM	Unix-like, Windows	Yes	LGPL	Yes	Yes
vasm	various	Yes	Free	No	Yes
Xenix	Xenix 2.3 and 3.0 (before 1985)	No	Proprietary	No	1982-1984
Yasm	Windows, DOS, Linux, Unix-like	Yes	BSD	Yes	Yes
Liquid^{[citation needed]}	Windows, DOS	No	Proprietary	Yes	Yes

^ Part of the Minix 3 source tree, but without obvious development activity. The full source history is available.
^ Developed by Interactive in 1986 when they ported System V to Intel iAPX286 and 80386 architectures. Archetypical of ATT syntax because it was used as reference for GAS. Still used for The SCO Group's products, UnixWare and OpenServer.
^ Home site does not appear active any more. Also offered as part of FreeBSD Ports, in bcc-1995.03.12.
^ Active and supported, but not advertised.
^ Developed in 1982 at MIT as a cross-assembler, it was picked up by Interactive in 1983 when they developed PC/IX under IBM contract. The syntax was later used as base for ACK assembler, to be used in Minix 1.x toolchain.
^ RosAsm project on WebArchive.org.
^ Part of the C++Builder Tool Chain, but not sold as a stand-alone product, or marketed since the CodeGear spin-off; Borland was still selling it until then. Version 5.0, the last, is dated 1996.
^ Turbo Assembler was developed as "Turbo Editasm" by Uriah Barnett from Speedware Inc (Sacramento, CA) between 1984 and 1987. It was later sold to (or marketed by) Borland as their Turbo Assembler.

Other

Assembler	License	Instruction set	Host platform
ALM (Assembly Language for Multics)	MIT License	GE-645 Honeywell 6180	GE-645 Honeywell 6180
Babbage	Proprietary	GEC 4000 series	GEC 4000 series
COMPASS^[1]	Proprietary	CDC mainframe	CDC mainframe
MACRO-10	Free	PDP-10	PDP-10
MACRO-11	Unknown	PDP-11	PDP-11
MACRO-32	Unknown	VAX	VAX
PASMO	GPL	Zilog Z80	numerous
SUPERAS	Public domain	Hitachi SH2	Win32
vasm	Free	Zilog Z80, Motorola 6800 family	various
MRS	GPL	Zilog Z80, 8080	ZX Spectrum, PMD-85
ASEM-51	Free	8051	Embedded Systems
GPASM	GPL	PIC microcontroller	many
ID3E	Free for academic use	SC123	SC123 emulator
MIPS	Free	MIPS instruction set	MIPS instruction set
Symbolic Optimal Assembly Program (SOAP)	Proprietary	IBM 650	IBM 650
MPW IIgs Assembler	Proprietary	WD 65C816	Apple IIgs
Meta-Symbol	Free	SDS/XDS Sigma systems	SDS/XDS Sigma systems
Autocoder^[2]	Free	IBM 705, 14xx, 1410, 7010, 7070, 7072, 7074, 7080	various
Fortran Assembly Program (FAP)	Free	IBM 709, 704x, 709x	various
Macro Assembly Program (MAP)	Free	IBM 709, 704x, 709x	various
Symbolic Programming System (SPS)^[3]	Free	IBM 14xx, 1620, 1710	IBM 1401, 1440, 1460, 1620, 1710
ASMB, ASBL, NSBL - Numeric op codes, used for 1900 Operating System Executive	Proprietary	ICL 1900	ICL 1900
GINerator mnemonic opcodes, used for GEORGE (operating system)	Proprietary	ICL 1900	ICL 1900
PLAN mnemonic opcodes, used for commercial 1900 programs	Proprietary	ICL 1900	ICL 1900
UTMOST	Unknown	UNIVAC III	UNIVAC III

Notes and references

^ COMPASS is a family of assemblers for disparate machines.
^ AUTOCODER is actually a family of assemblers for disparate machines.
^ SPS is actually a family of assemblers for disparate machines.

[1] COMPASS is a family of assemblers for disparate machines.

[2] AUTOCODER is actually a family of assemblers for disparate machines.

[3] SPS is actually a family of assemblers for disparate machines.

[1]

[2]

[3]

v t e x86 assembly topics
Topics	Assembly language Comparison of assemblers Disassembler Instruction set Low-level programming language Machine code Microassembler x86 assembly language
Assemblers	A86/A386 Flat Assembler (FASM) GNU Assembler (GAS) High Level Assembly (HLA) Microsoft Macro Assembler (MASM) Netwide Assembler (NASM) Turbo Assembler (TASM) Open Watcom Assembler (WASM)
Programming issues	Call stack Flags Carry flag Direction flag Interrupt flag Overflow flag Zero flag Memory address Opcode Program counter Processor register Calling conventions Instruction listings Registers