Fetching Gacha Records for Arknights: Endfield

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Before reading this article, you may want to read the following articles first to better understand the context.

Astrionyx – Wuthering Waves Gacha Analysis Tool & Details

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Today, Arknights: Endfield has officially entered its open beta phase. After spending some time exploring the game, I wanted to import my gacha data into my own gacha analysis app. However, possibly because the game had just launched, I was unable to find any existing tool capable of exporting gacha records. As a result, I decided to implement this functionality myself.

In this article, I will outline the core approach. Hopefully, this will be helpful if you are looking to achieve the same.

What’s in the URL

As with many other games, we can capture a gacha record request URL using a packet-sniffing tool:

TEXT

https://ef-webview.hypergryph.com/api/record/char?lang=zh-cn&seq_id={seqId}&pool_type={poolType}&token={token}&server_id={serverId}

Character Pool

For character pools, the two key parameters are pool_type and seq_id.

pool_type represents the pool enum value, and currently supports the following:

Beginner Search: E_CharacterGachaPoolType_Beginner
Standard Search: E_CharacterGachaPoolType_Standard
Special Search: E_CharacterGachaPoolType_Special

Unlike games such as Genshin Impact or Wuthering Waves, Endfield’s gacha record URLs typically include the seq_id parameter.

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From the examples above, we can derive several key properties of seq_id:

seq_id (seqId) is an account-level, cross-sub-pool, and pool-type-isolated incremental sequence. All character sub-pools share a single seq_id sequence, while weapon sub-pools share a separate one. Within the same pool category (all character pools or all weapon pools), switching between sub-pools does not reset the sequence.
A larger seq_id indicates a more recent record.
If the request omits the seq_id parameter, the API returns the latest five records (i.e., those with the largest seqId values).

From these observations, we can conclude: when browsing gacha history in-game from newest to oldest, the process corresponds to decrementing the seq_id parameter in successive API requests.

Additionally, each response includes a hasMore flag, which indicates whether there are more records available beyond the smallest seqId in the current response (i.e., whether pagination can continue).

Weapon Pool

The weapon pool API differs slightly from the character pool API. Retrieving weapon data requires two steps:

Fetch weapon pool list

First, retrieve the list of weapon pools for which the user has records:

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Response structure:

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Weapon pools fall into two categories:

Limited weapon pools: poolId follows the weponbox_* pattern (e.g., weponbox_1_0_1), corresponding to current featured weapons
Permanent weapon pools: poolId follows the weaponbox_constant_* pattern (e.g., weaponbox_constant_2)

Interestingly, the prefix wepon appears to be a typo of “weapon”, possibly a legacy artifact.

Fetch weapon gacha records

To retrieve records for a specific weapon pool, the API uses pool_id instead of pool_type:

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Response structure:

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Compared to character records, weapon records include:

weaponId: weapon identifier
weaponName: weapon name
weaponType: weapon category (e.g., E_WeaponType_Sword, E_WeaponType_Wand)

The seq_id behavior is identical: all weapon sub-pools share a unified sequence.

At this point, we have a clear understanding of how the gacha record API works in Arknights: Endfield.

Main Approach

Based on the above analysis, we can design a method to retrieve all gacha records using a valid API URL:

Character Pool

Start by selecting any pool_type and sending a request without seq_id to obtain the latest records (with the highest seqId).
Use the smallest seqId in the response as a cursor, and iteratively fetch older records until either:
- the server no longer returns additional data, or
- hasMore === false, indicating the earliest record has been reached.
Repeat the process for each pool_type.

Weapon Pool

Retrieve the list of weapon pools via the pool list API.
Iterate over each pool and fetch records using pool_id.
Classify pools based on poolId: those containing constant are permanent; others are limited.

Code Implementation

CodeBlock Loading...

With this approach, we can successfully retrieve the complete set of gacha records across all pools in Arknights: Endfield.

In this article, I will outline the core approach. Hopefully, this will be helpful if you are looking to achieve the same.

What’s in the URL

As with many other games, we can capture a gacha record request URL using a packet-sniffing tool:

TEXT

https://ef-webview.hypergryph.com/api/record/char?lang=zh-cn&seq_id={seqId}&pool_type={poolType}&token={token}&server_id={serverId}

Character Pool

For character pools, the two key parameters are pool_type and seq_id.

pool_type represents the pool enum value, and currently supports the following:

Beginner Search: E_CharacterGachaPoolType_Beginner
Standard Search: E_CharacterGachaPoolType_Standard
Special Search: E_CharacterGachaPoolType_Special

Unlike games such as Genshin Impact or Wuthering Waves, Endfield’s gacha record URLs typically include the seq_id parameter.

JSON

// seq_id=26&pool_type=E_CharacterGachaPoolType_Standard
{
  "code": 0,
  "data": {
    "list": [
      //...
      {
        "poolId": "standard",
        "poolName": "基础寻访",
        "charId": "chr_0019_karin",
        "charName": "秋栗",
        "rarity": 4,
        "isFree": false,
        "isNew": false,
        "gachaTs": "1769073164712",
        "seqId": "21"
      }
    ],
    "hasMore": false
  },
  "msg": ""
}

// pool_type=E_CharacterGachaPoolType_Beginner
{
  "code": 0,
  "data": {
    "list": [
      {
        "poolId": "beginner",
        "poolName": "启程寻访",
        "charId": "chr_0022_bounda",
        "charName": "萤石",
        "rarity": 4,
        "isFree": false,
        "isNew": false,
        "gachaTs": "1769072324787",
        "seqId": "20" // the most recent record in this pool
      },
      // ...
    ],
    "hasMore": true
  },
  "msg": ""
}

CodeBlock Loading...

From the examples above, we can derive several key properties of seq_id:

seq_id (seqId) is an account-level, cross-sub-pool, and pool-type-isolated incremental sequence. All character sub-pools share a single seq_id sequence, while weapon sub-pools share a separate one. Within the same pool category (all character pools or all weapon pools), switching between sub-pools does not reset the sequence.
A larger seq_id indicates a more recent record.
If the request omits the seq_id parameter, the API returns the latest five records (i.e., those with the largest seqId values).

From these observations, we can conclude: when browsing gacha history in-game from newest to oldest, the process corresponds to decrementing the seq_id parameter in successive API requests.

Weapon Pool

The weapon pool API differs slightly from the character pool API. Retrieving weapon data requires two steps:

Fetch weapon pool list

First, retrieve the list of weapon pools for which the user has records:

TEXT

https://ef-webview.hypergryph.com/api/record/weapon/pool?lang=zh-cn&token={token}&server_id={serverId}

CodeBlock Loading...

Response structure:

JSON

{
  "code": 0,
  "data": [
    { "poolId": "weponbox_1_0_1", "poolName": "熔铸申领" },
    { "poolId": "weaponbox_constant_2", "poolName": "星声申领" }
    // ...
  ],
  "msg": ""
}

CodeBlock Loading...

Weapon pools fall into two categories:

Limited weapon pools: poolId follows the weponbox_* pattern (e.g., weponbox_1_0_1), corresponding to current featured weapons
Permanent weapon pools: poolId follows the weaponbox_constant_* pattern (e.g., weaponbox_constant_2)

Interestingly, the prefix wepon appears to be a typo of “weapon”, possibly a legacy artifact.

Fetch weapon gacha records

To retrieve records for a specific weapon pool, the API uses pool_id instead of pool_type:

TEXT

https://ef-webview.hypergryph.com/api/record/weapon?lang=zh-cn&seq_id={seqId}&pool_id={poolId}&token={token}&server_id={serverId}

CodeBlock Loading...

Response structure:

JSON

{
  "code": 0,
  "data": {
    "list": [
      {
        "poolId": "weponbox_1_0_1",
        "poolName": "熔铸申领",
        "weaponId": "wpn_funnel_0010",
        "weaponName": "骑士精神",
        "weaponType": "E_WeaponType_Wand",
        "rarity": 6,
        "isNew": true,
        "gachaTs": "1769238381938",
        "seqId": "47"
      },
      // ...
    ],
    "hasMore": true
  },
  "msg": ""
}

CodeBlock Loading...

Compared to character records, weapon records include:

weaponId: weapon identifier
weaponName: weapon name
weaponType: weapon category (e.g., E_WeaponType_Sword, E_WeaponType_Wand)

The seq_id behavior is identical: all weapon sub-pools share a unified sequence.

At this point, we have a clear understanding of how the gacha record API works in Arknights: Endfield.

Main Approach

Based on the above analysis, we can design a method to retrieve all gacha records using a valid API URL:

Character Pool

Start by selecting any pool_type and sending a request without seq_id to obtain the latest records (with the highest seqId).
Use the smallest seqId in the response as a cursor, and iteratively fetch older records until either:
- the server no longer returns additional data, or
- hasMore === false, indicating the earliest record has been reached.
Repeat the process for each pool_type.

Weapon Pool

Retrieve the list of weapon pools via the pool list API.
Iterate over each pool and fetch records using pool_id.
Classify pools based on poolId: those containing constant are permanent; others are limited.

Code Implementation

// Fetch character pool records
async function fetchCharacterRecords(token: string, serverId: string) {
  const poolTypes = [
    "E_CharacterGachaPoolType_Beginner",
    "E_CharacterGachaPoolType_Standard",
    "E_CharacterGachaPoolType_Special",
  ];
  const allRecords = [];

  for (const poolType of poolTypes) {
    let cursor = null;
    let hasMore = true;

    while (hasMore) {
      const seqIdParam = cursor !== null ? `&seq_id=${cursor}` : "";
      const url = `https://ef-webview.hypergryph.com/api/record/char?lang=zh-cn${seqIdParam}&pool_type=${poolType}&token=${encodeURIComponent(token)}&server_id=${serverId}`;
      
      const response = await fetch(url);
      const { data } = await response.json();

      if (data?.list?.length > 0) {
        allRecords.push(...data.list);
        hasMore = data.hasMore;
        
        if (hasMore) {
          const seqIds = data.list.map(item => Number(item.seqId));
          cursor = Math.min(...seqIds);
          await new Promise(resolve => setTimeout(resolve, 300));
        }
      } else {
        hasMore = false;
      }
    }
  }

  return allRecords;
}

// Fetch weapon pool records
async function fetchWeaponRecords(token: string, serverId: string) {
  const allRecords = [];
  const poolListUrl = `https://ef-webview.hypergryph.com/api/record/weapon/pool?lang=zh-cn&token=${encodeURIComponent(token)}&server_id=${serverId}`;
  const poolListResponse = await fetch(poolListUrl);
  const { data: weaponPools } = await poolListResponse.json();

  if (!weaponPools?.length) return allRecords;

  for (const pool of weaponPools) {
    let cursor = null;
    let hasMore = true;

    while (hasMore) {
      const seqIdParam = cursor !== null ? `&seq_id=${cursor}` : "";
      const url = `https://ef-webview.hypergryph.com/api/record/weapon?lang=zh-cn${seqIdParam}&pool_id=${pool.poolId}&token=${token}&server_id=${serverId}`;
      
      const response = await fetch(url);
      const { data } = await response.json();

      if (data?.list?.length > 0) {
        allRecords.push(...data.list);
        hasMore = data.hasMore;
        
        if (hasMore) {
          const seqIds = data.list.map(item => Number(item.seqId));
          cursor = Math.min(...seqIds);
          await new Promise(resolve => setTimeout(resolve, 300));
        }
      } else {
        hasMore = false;
      }
    }
  }

  return allRecords;
}

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With this approach, we can successfully retrieve the complete set of gacha records across all pools in Arknights: Endfield.