You can connect Budapest with Slovenian Way of St.James (Slovenska Jakobova pot: http://www.jakobova-pot.si/). There are two branches from east/northeast to Ljubljana:
- Dolenjska Branch starts at Croatian border,
- Prekmursko-štajerska Branch starts at Hungarian border.
Both are marked and merge in capitol city of Ljubljana. From there you can walk Gorenjska Branch to the north (Austria) or Primorska Branch to the southwest (Italy. Trieste). There is also a guidebook but unfortunately only in Slovenian.
These are Caminos but there are at least three other marked trails if you want to use them in Slovenia:
- Slovenian Mountain Trail (oldest continuous and marked trail in the world),
- European Peace Walk trail,
- Alpe Adria Trail.