cs2-masked-inspect (JavaScript)

Pure JavaScript library for encoding and decoding CS2 masked inspect links — no external dependencies.

Installation

npm install @vlydev/cs2-masked-inspect

Usage

Deserialize a CS2 inspect link

const { InspectLink } = require('@vlydev/cs2-masked-inspect');

// Accepts a full steam:// URL or a raw hex string
const item = InspectLink.deserialize(
  'steam://run/730//+csgo_econ_action_preview%20E3F3367440334DE2FBE4C345E0CBE0D3...'
);

console.log(item.defIndex);   // 7  (AK-47)
console.log(item.paintIndex); // 422
console.log(item.paintSeed);  // 922
console.log(item.paintWear);  // ~0.04121
console.log(item.itemId);     // 46876117973

item.stickers.forEach(s => console.log(s.stickerId));
// 7436, 5144, 6970, 8069, 5592

Serialize an item to a hex payload

const { InspectLink, ItemPreviewData } = require('@vlydev/cs2-masked-inspect');

const data = new ItemPreviewData({
  defIndex:  60,
  paintIndex: 440,
  paintSeed:  353,
  paintWear:  0.005411375779658556,
  rarity:     5,
});

const hex = InspectLink.serialize(data);
// 00183C20B803280538E9A3C5DD0340E102C246A0D1

const url = `steam://run/730//+csgo_econ_action_preview%20${hex}`;

Item with stickers and keychains

const { InspectLink, ItemPreviewData, Sticker } = require('@vlydev/cs2-masked-inspect');

const data = new ItemPreviewData({
  defIndex:  7,
  paintIndex: 422,
  paintSeed:  922,
  paintWear:  0.04121,
  rarity:     3,
  quality:    4,
  stickers: [
    new Sticker({ slot: 0, stickerId: 7436 }),
    new Sticker({ slot: 1, stickerId: 5144, wear: 0.1 }),
  ],
});

const hex     = InspectLink.serialize(data);
const decoded = InspectLink.deserialize(hex); // round-trip

---

Gen codes

Generate a Steam inspect URL from item parameters (defindex, paintindex, paintseed, paintwear):

const { toGenCode, generate, parseGenCode, ItemPreviewData } = require('@vlydev/cs2-masked-inspect');

// Generate a Steam inspect URL from item parameters
const url = generate(7, 474, 306, 0.22540508);
// steam://rungame/730/76561202255233023/+csgo_econ_action_preview%20...

// Convert ItemPreviewData to a gen code string
const item = new ItemPreviewData({ defIndex: 7, paintIndex: 474, paintSeed: 306, paintWear: 0.22540508 });
toGenCode(item);          // "!gen 7 474 306 0.22540508"
toGenCode(item, '!g');    // "!g 7 474 306 0.22540508"

// Parse a gen code back to ItemPreviewData
const item2 = parseGenCode('!gen 7 474 306 0.22540508');

// Convert an existing inspect link directly to a gen code
const { genCodeFromLink } = require('@vlydev/cs2-masked-inspect');
const code = genCodeFromLink('steam://rungame/730/76561202255233023/+csgo_econ_action_preview%20001A...');
// "!gen 7 474 306 0.22540508"

---

Validation

Use InspectLink.isMasked() and InspectLink.isClassic() to detect the link type without decoding it.

const { InspectLink } = require('@vlydev/cs2-masked-inspect');

// New masked format (pure hex blob) — can be decoded offline
const maskedUrl = 'steam://run/730//+csgo_econ_action_preview%20E3F3...';
InspectLink.isMasked(maskedUrl);   // true
InspectLink.isClassic(maskedUrl);  // false

// Hybrid format (S/A/D prefix with hex proto after D) — also decodable offline
const hybridUrl = 'steam://rungame/730/.../+csgo_econ_action_preview%20S76561199323320483A50075495125D1101C4C4FCD4AB10...';
InspectLink.isMasked(hybridUrl);   // true
InspectLink.isClassic(hybridUrl);  // false

// Classic format — requires Steam Game Coordinator to fetch item info
const classicUrl = 'steam://rungame/730/.../+csgo_econ_action_preview%20S76561199842063946A49749521570D2751293026650298712';
InspectLink.isMasked(classicUrl);  // false
InspectLink.isClassic(classicUrl); // true

---

Validation rules

deserialize() enforces:

Rule	Limit	Error
Hex payload length	max 4,096 characters	RangeError
Protobuf field count	max 100 per message	RangeError

serialize() enforces:

Field	Constraint	Error
paintWear	[0.0, 1.0]	RangeError
customName	max 100 characters	RangeError

---

How the format works

Three URL formats are handled:

1. New masked format — pure hex blob after csgo_econ_action_preview:

   steam://run/730//+csgo_econ_action_preview%20<hexbytes>
   

2. Hybrid format — old-style S/A/D prefix, but with a hex proto appended after D (instead of a decimal did):

   steam://rungame/730/.../+csgo_econ_action_preview%20S<steamid>A<assetid>D<hexproto>
   

3. Classic format — old-style S/A/D with a decimal did; requires Steam GC to resolve item details.

For formats 1 and 2 the library decodes the item offline. For format 3 only URL parsing is possible.

The hex blob (formats 1 and 2) has the following binary layout:

[key_byte] [proto_bytes XOR'd with key] [4-byte checksum XOR'd with key]

Section	Size	Description
key_byte	1 byte	XOR key. 0x00 = no obfuscation (tool links). Other values = native CS2 links.
proto_bytes	variable	CEconItemPreviewDataBlock protobuf, each byte XOR'd with key_byte.
checksum	4 bytes	Big-endian uint32, XOR'd with key_byte.

Checksum algorithm

const buffer  = Buffer.concat([Buffer.from([0x00]), protoBytes]);
const crc     = crc32(buffer);                          // standard CRC32
const xored   = ((crc & 0xFFFF) ^ (protoBytes.length * crc)) >>> 0;
const checksum = Buffer.alloc(4);
checksum.writeUInt32BE(xored, 0);                       // big-endian uint32

paintWear encoding

paintWear is stored as a uint32 varint whose bit pattern is the IEEE 754 representation of a float32. The library handles this transparently — callers always work with regular JavaScript number values.

---

Proto field reference

CEconItemPreviewDataBlock

Field	Number	Type	JS property
accountid	1	uint32	accountId
itemid	2	uint64	itemId
defindex	3	uint32	defIndex
paintindex	4	uint32	paintIndex
rarity	5	uint32	rarity
quality	6	uint32	quality
paintwear	7	uint32*	paintWear (float32 reinterpreted as uint32)
paintseed	8	uint32	paintSeed
killeaterscoretype	9	uint32	killEaterScoreType
killeatervalue	10	uint32	killEaterValue
customname	11	string	customName
stickers	12	repeated Sticker	stickers
inventory	13	uint32	inventory
origin	14	uint32	origin
questid	15	uint32	questId
dropreason	16	uint32	dropReason
musicindex	17	uint32	musicIndex
entindex	18	int32	entIndex
petindex	19	uint32	petIndex
keychains	20	repeated Sticker	keychains

Sticker

Field	Number	Type	JS property
slot	1	uint32	slot
sticker_id	2	uint32	stickerId
wear	3	float32	wear
scale	4	float32	scale
rotation	5	float32	rotation
tint_id	6	uint32	tintId
offset_x	7	float32	offsetX
offset_y	8	float32	offsetY
offset_z	9	float32	offsetZ
pattern	10	uint32	pattern

---

Known test vectors

Vector 1 — Native CS2 link (XOR key 0xE3)

E3F3367440334DE2FBE4C345E0CBE0D3E7DB6943400AE0A379E481ECEBE2F36F
D9DE2BDB515EA6E30D74D981ECEBE3F37BCBDE640D475DA6E35EFCD881ECEBE3
F359D5DE37E9D75DA6436DD3DD81ECEBE3F366DCDE3F8F9BDDA69B43B6DE81EC
EBE3F33BC8DEBB1CA3DFA623F7DDDF8B71E293EBFD43382B

Field	Value
itemId	46876117973
defIndex	7 (AK-47)
paintIndex	422
paintSeed	922
paintWear	≈ 0.04121
rarity	3
quality	4
sticker IDs	[7436, 5144, 6970, 8069, 5592]

Vector 2 — Tool-generated link (key 0x00)

new ItemPreviewData({ defIndex: 60, paintIndex: 440, paintSeed: 353,
                      paintWear: 0.005411375779658556, rarity: 5 })

Expected hex:

00183C20B803280538E9A3C5DD0340E102C246A0D1

---

Running tests

npm test

36 tests using the Node.js built-in node:test runner — no external test framework required.

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Contributing

Bug reports and pull requests are welcome on GitHub.

1. Fork the repository
2. Create a branch: git checkout -b my-fix
3. Make your changes and add tests
4. Ensure all tests pass: npm test
5. Open a Pull Request

All PRs require the CI checks to pass before merging.

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Author

VlyDev — vladdnepr1989@gmail.com

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License

MIT © VlyDev