Some of the most commonly used SAP ABAP/BASIS Transaction Codes are listed below:
(Since the list of ABAP/BASIS trasaction codes were very big, so I have posted this list in two parts. This post is Part 1. To find more ABAP/BASIS transaction codes visit Part 2 at Standard ABAP/BASIS Transaction Codes : Part2)

           
Transaction Code Description
ABAPDCOU ABAP Documentation
AL01 SAP Alert Monitor
AL02 Database Alert Monitor
AL03 Operating System Alert Monitor
AL04  Monitor call distribution
AL05 Workload Alert Monitor
AL06  Performance: Upload/Download
AL07  Early Watch Report
AL08 Current Active Users
AL09  Data for database expertise
AL10  Download to Early Watch
AL11 Display operating system file from CCMS
AL12  Display table buffer (Exp. session)
AL13  Display Shared Memory (Expert mode)
AL15  Customize SAPOSCOL destination
AL16 Local Alert Monitor for Operating System
AL17  Remote Alert Monitor for Operat. Syst.
AL18 Local File System Monitor
AL19  Remote File System Monitor
AL20  Early Watch Data Collector List
AL21  ABAP Program analysis
AL22 Dependent objects display
BAOV Add-On Version Information
BAPI BAPI Explorer
BD54 Maintain Logical Systems
BUSP Regenerate screens during BDT development
CMOD Enhancements
DB01 Analyze exclusive lockwaits
DB02 Analyze tables and indexes
DB03 Parameter changes in database
DB05 Analysis of table with respect to indexed fields
DB11  Early Watch Profile Maintenance
DB12 DB Backup Monitor
DB13 DBA Planning Calendar
DB14 DBA logs
DB15 Data Archiving: Database Tables
DB16  DB System Check: Monitor
DB17  DB System Check: Configuration
DB2   Select Database Activities
DB20  DB Cost-Based Optimizer: Tab. Stats
DB21  DB Cost-Based Optimizer: Config.
DB24  Database Operations Monitor
DB26  DB Profile:Monitor and Configuration
DB2J  Manage JCL jobs for OS/390
DBCO  Database Connection Maintenance
DI02 ABAP/4 Repository Information System: Tables.
DMIG  Start Transaction for Data Migration
FILE Cross-Client File Names/Paths
HIER Internal Application Component Hierarchy Maintenance
ICON Display Icons
LSMW Legacy System Migration Workbench
OAA1  SAP ArchiveLink: Maint.user st.syst
OAA3  SAP ArchiveLink protocols
OAA4  SAP ArchiveLink applic.maintenance
OAAD  ArchiveLink Administration Documents
OAC2  SAP ArchiveLink: Globaldoc. types
OAC5  SAP ArchiveLink: Bar code entry
OACA  SAP ArchiveLink workflow parameters
OAD0  SAP ArchiveLink: Objectlinks
OAD2  SAP ArchiveLink document classes
OAD3  SAP ArchiveLink: Link tables
OAD4  SAP ArchiveLink: Bar code types
OAD5  SAP ArchiveLink: Customizing Wizard
OADR  SAP ArchiveLink: Print list search
OAM1  SAP ArchiveLink: Monitoring
OAOR Business document navigator
OARE  SAP ArchiveLink:St.syst.return codes
OLE Examples for OLE Processing
OS01 LAN check with ping
OS03  O/S Parameter changes
OS04  Local System Configuration
OS05  Remote System Cconfiguration
OS06  Local Operating System Activity
OS07  Remote Operating SystemActivity
OSS1 SAP Online Service System
OY08  Development Class Overview
OY18  Table history
OY19 Compare Tables
PFCG Profile Generator (Activity Group Maintenance)
PFUD User Master Data Reconciliation
PFTC Workflow
RLOG  Data migration logging
RZ01 Graphical background job scheduling monitor
RZ02 Network graphical display of instance
RZ03 Presentation, Control SAP Instances
RZ04 Maintain Operation Modes and Instances
RZ06 Maintain alert threshold
RZ08 CCMS Alert Monitor
RZ10 Maintain system profiles
RZ11 Profile parameter maintenance
RZ12  Maintain RFC Server Group Assignment
RZ20 CCMS Monitoring
RZ21 Customize CCMS Alert Monitor
S001 ABAP/4 Development Weorkbench
S002 System Administration
SA38 Execute a program and ABAP reporting
SAD0  Address Management call
SADC  Address: Maint. communication types
SAINT Plug-in Installation
SALE IDoc and ALE development
SARI  Archive Information System
SAR3  Customizing Archiving
SAR4  Define Archiving Class
SAR5  Assign Archiving Class
SAR6  Archiving Time Generator
SARA Archive Management
SARL  Call of ArchiveLink Monitor  
SARP  Reporting (Tree Structure): Execute
SART  Display Reporting Tree
SB01  Business Navigator - Component View
SB02  Business Navigator - Process flow view
SBAS  Assignments to Process Model Elemts
SC38  Start Report Immediately
SCAM CATT management
SCAT Computer Aided Test Tool
SCC0  Client Copy
SCC1 Client Copy - Special Selections
SCC2  Client transport
SCC3 Client copy log
SCC4 Client copy administration
SCC5 Delete clients
SCC6 Client import
SCC7 Client import – post processing
SCC8 Client export
SCC9 Remote client copy
SCCL Local client copy
SCDO Display Change Document Objects
SCMP View/Table comparison
SCOM  SAPcomm: Configuration
SCON  SAPconnect - Administration
SCOT SAPconnect Administration
SCPF  Generate enterprise IMG
SCPR1 Customizing Profiles : Maintenance Tool
SCPR2 Comparing Customizing profiles
SCU0 Compare Tables
SCU1  Table Comparison - Export to Tape
SCU2  Table Comparison Against Tape
SCU3 Table history
SCUA  Central User Administration : Distribution Model Assigment
SCUG  Central User Administration Structure Display
SCUM  Central User Administration Field Selection
SD11 Data Modeler
SDBE  Explain an SQL Statement
SECR  Audit Information System
SE01 Transport Organizer
SE03 Transport Utilities
SE06 Set Up Workbench Organizer
SE07 CTS Status Display
SE09 Workbench Organizer
SE10 Customizing Organizer
SE11 ABAP/4 Dictionary Maintenance
SE12 ABAP/4 Dictionary Display
SE13 Maintain Technical Settings (Tables)
SE14 Utilities for Dictionary Tables
SE15 ABAP/4 Repository Information System
SE16 Data Browser
SE16N Table Browser (the N stands for New, it replaces SE16)
SE17 General Table Display
SE24 Class Builder
SE30 ABAP/4 Runtime Analysis
SE32 ABAP/4 Text Element Maintenance
SE33  Context Builder
SE35 ABAP/4 Dialog Modules
SE36 ABAP/4 Logical Databases
SE37 ABAP/4 Function Modules
SE38 ABAP Editor
SE39 Splitscreen Editor: Program Compare
SE40  MP: Standards Maint. and Translation
SE41 Menu Painter
SE43 Maintain Area Menu
SE48 Show program call hierarchy. Very useful to see the overall structure of a program
SE49 Table manipulation. Show what tables are behind a transaction code
SE51 Screen Painter: Initial Screen
SE52  Parameterized screenpainter call
SE54 Generate View Maintenance Module
SE55  Internal table view maintenance call
SE56  Internal call: display table view
SE61 R/3 Documentation
SE62 Industry utilities
SE63 Translation
SE64 Terminology
SE65 R/3 document. short text statistics SE66 R/3 Documentation Statistics (Test!)
SE68 Translation Administration
SE71 SAPScript Layouts
SE72 SAPscript styles
SE73 SAPscript font maintenance (revised)
SE74 SAPscript format conversion
SE75 SAPscript Settings
SE76 SAPscript Translation Layout Sets
SE77 SAPscript Translation Styles
SE78  SAPscript Graphics administration
SE80 ABAP/4 Development Workbench
SE81 SAP Application Hierarchy
SE82 Customer Application Hierarchy
SE83 Reuse Library. Provided by Smiho Mathew
SE84 ABAP/4 Repository Information System
SE85 ABAP/4 Dictionary Information System
SE86 ABAP/4 Repository Information System
SE87 Data Modeler Information System
SE88 Development Coordination Info System
SE89  Maintain Trees in Information System
SE91 Maintain Messages
SE92 Maintain system log messages
SE93 Maintain Transaction Codes
SE94  Customer enhancement simulation
SE95 Modification Browser
SEARCH_SAP_MENU Find menu path for transaction code
SEPS  SAP Electronic Parcel Service
SERP  Reporting: Change Tree Structure
SEU Object Repository Browser
SF01  Client-Specific File Names
SFAW  Field Selection Maintenance

To find more ABAP/BASIS transaction codes visit Standard ABAP/BASIS Transaction Codes : Part2)

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