Format comparison: abapGit vs gCTS / AFF

Goal

Pick the right --format for adt checkout, adt checkin, and adt import. Both formats are supported by adt-cli via plugins:

--format abapgit — the classic abapGit layout (@abapify/adt-plugin-abapgit). Default.
--format gcts — gCTS / AFF layout (@abapify/adt-plugin-gcts).

Side-by-side

Aspect	abapGit classic	gCTS / AFF
Primary driver	abapGit (client-side)	SAP gCTS (server-side)
Source extension	`.<type>.abap` (e.g. `zcl_foo.clas.abap`)	`.<type>.abap`
Metadata format	XML (`<DD02V>`, `<VSEOCLASS>`, ...)	JSON (`{ "header": { ... } }`)
Metadata extension	`.<type>.xml`	`.<type>.json`
DDL source	`.ddls.asddls`	`.ddls.asddls`
Includes (class)	`zcl_foo.clas.locals_imp.abap`, `...locals_def.abap`, `...testclasses.abap`	Same filenames, plus a JSON index
Package folder layout	Flat (one dir per TADIR package)	Hierarchical (nested directories mirror nested packages)
Object index	(none — files are the index)	`.aff-manifest.json` at the root
Typical consumer	Local git client, CI pipelines	SAP gCTS (`/sap/bc/cts_abapvcs/*`)
Standardised by	abapGit community	SAP (AFF = ABAP File Format)
File encoding	UTF-8	UTF-8
Line endings	LF	LF

Example: a single class

abapGit:

src/
  zcl_demo.clas.abap
  zcl_demo.clas.xml
  zcl_demo.clas.locals_imp.abap
  zcl_demo.clas.testclasses.abap

zcl_demo.clas.xml (excerpt):

<?xml version="1.0" encoding="utf-8"?>
<abapGit version="v1.0.0" serializer="LCL_OBJECT_CLAS" serializer_version="v1.0.0">
 <asx:abap xmlns:asx="http://www.sap.com/abapxml" version="1.0">
  <asx:values>
   <VSEOCLASS>
    <CLSNAME>ZCL_DEMO</CLSNAME>
    <LANGU>E</LANGU>
    <DESCRIPT>Demo class</DESCRIPT>
   </VSEOCLASS>
  </asx:values>
 </asx:abap>
</abapGit>

gCTS / AFF:

src/
  zmypkg/
    zcl_demo/
      zcl_demo.clas.abap
      zcl_demo.clas.json
      zcl_demo.clas.locals_imp.abap
      zcl_demo.clas.testclasses.abap

zcl_demo.clas.json:

{
  "formatVersion": "1",
  "header": {
    "description": "Demo class",
    "originalLanguage": "en"
  },
  "class": {
    "classCategory": "generalObjectType",
    "classPoolType": "classPool"
  }
}

Example: a table

File	abapGit	gCTS / AFF
`zt_customer.tabl.xml`	✅ (XML, DD02V/DD03P nested)	❌
`zt_customer.tabl.json`	❌	✅ (JSON, flat `fields[]`)

No .abap for DDIC objects in either format — they're metadata-only.

Pick the right format

You want to...	Use
Store ABAP in GitHub and round-trip via abapGit	abapgit
Use SAP's native server-side git (gCTS)	gcts
Interop with existing abapGit repos	abapgit
Start fresh on a greenfield S/4 project	gcts (SAP's forward direction)
Validate with `xmllint`	abapgit (XML schemas available)
Use standard JSON tooling (jq, JSON Schema)	gcts

Switching between them

adt checkin and adt import accept --format — the same source package can be serialised both ways:

adt checkout package \$ZDEMO ./abapgit --format abapgit
adt checkout package \$ZDEMO ./aff     --format gcts

# Round-trip back with either
adt checkin ./abapgit -p \$ZDEMO -t $TR
adt checkin ./aff     -p \$ZDEMO -t $TR --format gcts

The two directories are not byte-equivalent — same SAP objects, different serialisations.

Goal​

Side-by-side​

Example: a single class​

Example: a table​

Pick the right format​

Switching between them​

See also​