A map of geographical extension of dialects of languages that belong into South Slavic group (Slovene, Serbo-Croatian, Macedonian, Bulgarian). Bigger groups of dialect are named. Slovene and Kajkavian are further split by thin grey lines to indicate dialects.
Legend:

Slovene:
  Carinthian dialect group
  Upper Carniolan dialect group
  Rovte dialect group
  Littoral dialect group
  Lower Carniolan dialect group
  Styrian dialect group
  Pannonian dialect group
Kajkavian:
  Goran dialect
  Prigorje dialect
  Turopolje–Posavina dialect
  Zagorje–Međimurje dialect
  Križevci–Podravina dialect
  Lower Sutlan dialect
Chakavian
  Buzet dialect
  Northern Chakavian
  Middle Chakavian
  Southwest Istrian
  Southern Chakavian
  Southeastern Chakavian (circled)
Shtokavian
  Slavonian dialect
  East Bosnian dialect
  Molise Slavic (circled)
  Younger Ikavian dialect
  Eastern Herzegovinian dialect
  Šumadija–Vojvodina dialect
  Smederevo–Vršac dialect
  Kosovo–Resava dialect
  Zeta–South Raška dialect
Torlakian (names given by SerboCroatian linguists):
  Prizren–South Morava dialect
  Svrljig–Zaplanje dialect
  Timok–Lužnica dialect
Macedonian
  Northern dialects
  Western dialects
  Central dialects
  Eastern dialects
  Southern dialects
Bulgarian
  Southwestern Bulgarian dialects
  Northwestern Bulgarian dialects
  Western Rup dialects
  Central Rup dialects
  Thracian dialect
  Strandzha dialect
  Balkan dialects
  Moesian dialects
  Banat Bulgarian (circled)
The map is a collection of many maps of regional dialects of different languages. Therefore, the borders between languages might not match at all places the one normally present for that language because it overlaps with a border from other language's map. This map was made only by overlaying screenshots of maps, so it should not be used for precise determination. Note that in some areas other (non-slavic) languages might also be spoken or even prevailing (e. g. Kosovo, Hungary and Romania)
The coast and the border were taken from Eurostat (https://ec.europa.eu/eurostat/web/gisco/geodata/reference-data/administrative-units-statistical-units/countries).
Map of Slovene dialects and Slovene-Croatian border is based on this map.
Borders between Serbo-Croatian supradialects are based on (Kapović, 2015 pp.50–51). Chakavian borders are based on (Kapović, 2015, p. 43), Schakavian, Torlakian and Shtokavian are based on (Kapović, 2015, pp. 40–41). Kajkavian is based on Lončarić's map with addition of (Kapović, 2015 p. 46). Burgenland croatian is based on this file while Molise Slavic is based on its Wikipedia page as of April 2023. Border with Macedonian/Bulgarian is based on Kapović's map.

Kapović, Mate (2015)    (in Croatian)   Povijest hrvatske akcentuacije, Zagreb:  Zaklada HAZU, p. 50  ISBN:  978-953-150-971-8. Bulgarian is based on the interactive map.

See also the talk on South Slavic languages and creator's talk page for further updates.
Garygo golob