Hearthstone Deckstrings

The Hearthstone Deckstring format is a base64-encoded compact byte string, which losslessly encodes an arbitrary Hearthstone deck.

The purpose of the format is to allow players to share Hearthstone decks, import them into or export them from Hearthstone.


The format uses DBF IDs to represent cards. DBF IDs are found in the game files. A reference API is available on HearthstoneJSON.


The deckstring is a base64-encoded byte string. We decode it first.

Unless specified otherwise, every value that follows is an integer, encoded as an unsigned varint.

1. Header block

  1. Reserved byte 0x00
  2. Version (1)
  3. Format

The deckstring begins with the byte 0x00. It is then followed by the encoding version number. The version is currently always 1.

The Format value is a varint representing Standard or Wild. Its actual value is a FormatType enum.

2. Cards block

The cards block is split in four pairs of length + array in the following order:

  1. Heroes
  2. Single-copy cards
  3. 2-copy cards
  4. n-copy cards

Each pair has a leading varint specifying the number of items in the array. For the first three blocks, those are arrays of varints. For the last block, it is an array of pairs of varints. The goal of this structure is to make the deckstring as compact as possible. Each card is represented with a varint DBF ID as mentioned before.

Heroes: An array of initial heroes present in the deck. In other words, which hero the deck was made for. You should really always expect one. Additional note: The hero’s class determines which class the deck is for, but the deck is ostensibly made for a hero, not a class. If the specified hero is a hero skin, it will be used instead of the main hero iff available.

Note on heroes: Although it is an array, it is used for the initial hero, not playable heroes (such as the Frozen Throne heroes). If you can draw it, do not use this array.

Single-copy cards: Cards for which there is exactly one copy in the deck. 2-copy cards: Cards for which there is exactly two copies in the deck.

n-copy cards: All other cards in the deck. This array is a list of varint pairs, representing first the dbf id, followed by the amount of times that card is present in the deck. This SHOULD only contain cards with a minimum of 3 instances in the deck, which means that it will (at this time) always be empty for constructed decks; however it can theoretically contain single and double copy cards as well.

Although final ordering does not matter, cards are sorted by ascending DBF ID in their respective array in order to consistently generate the same deckstrings for the same decks. We call deckstrings where all card lists (including heroes) are sorted this way canonical deckstrings. The reference implementations below should already be generating canonical deckstrings.


When pasted into Hearthstone, the client will disregard any line beginning with the # character, which allows inserting comments into the string. One exception is the first line beginning with ### preceding the deck string, which will be used as the deck name if available.



The python-hearthstone library for Python 3 contains a hearthstone.deckstrings module which allows encoding and decoding of deckstrings.

from hearthstone.deckstrings import Deck
from hearthstone.enums import FormatType

# Create a deck from a deckstring
deck = Deck()
deck.heroes = [7]  # Garrosh Hellscream
deck.format = FormatType.FT_WILD
# Nonsense cards, but the deckstring doesn't validate.
deck.cards = [(1, 3), (2, 3), (3, 3), (4, 3)]  # id, count pairs
print(deck.as_deckstring)  # "AAEBAQcAAAQBAwIDAwMEAw=="

# Import a deck from a deckstring
deck = Deck.from_deckstring("AAEBAQcAAAQBAwIDAwMEAw==")
assert deck.heroes == [7]
assert deck.format == FormatType.FT_WILD
assert deck.cards == [(1, 3), (2, 3), (3, 3), (4, 3)]


The deckstrings library on npm can be used to encode and decode deckstrings.

import {encode, decode} from "deckstrings";

const deck = {
	cards: [[1, 3], [2, 3], [3, 3], [4, 3]], // [dbfid, count] pairs
	heroes: [7], // Garrosh Hellscream
	format: 1, // 1 for Wild, 2 for Standard

const deckstring = encode(deck);
console.log(deckstring); // AAEBAQcAAAQBAwIDAwMEAw==

const decoded = decode(deckstring);
console.log(JSON.stringify(deck) === JSON.stringify(decoded)); // true

C# / .NET

HearthDbs Deckstrings.DeckSerializer can be used to decode and encode deck strings.

// (Pseudocode)
using HearthDb.Deckstrings;

var deck = new Deck
	HeroDbfId = 7,
	CardDbfIds = new Dictionary()
		{1, 3}, {2, 3}, {3, 3}, {4, 3} // {dbfId, count}
	Format = FormatType.FT_WILD,

//Serialize deck object to deckstring
var deckstring = DeckSerializer.Serialize(deck);
Console.WriteLine(deckstring); // AAEBAQcAAAQBAwIDAwMEAw==

//Deserialize deckstring to deck object
var serialized = DeckSerializer.Deserialize(deckString);
Assert.AreEqual(deck, serialized);

For example usage see HearthDb.Tests.DeckSerializerTest.