# ULID / NanoID / KSUID / Snowflake ID Decoder Decode lexically sortable IDs losslessly with BigInt: ULID (Crockford base32), KSUID (base62), NanoID, MongoDB ObjectId, and Discord/Twitter/Sonyflake Snowflakes — with ISO timestamps, raw hex, bit-level field breakdowns and birthday-bound collision probabilities. > Canonical page: https://elysiatools.com/en/tools/ulid-nanoid-ksuid-snowflake-id-decoder - **Category:** Development - **Keywords:** ulid decoder, ksuid decoder, nanoid, snowflake decoder, objectid, crockford base32, collision probability ## Overview ULID: 48-bit millisecond timestamp + 80-bit randomness across 26 Crockford base32 characters. KSUID: 32-bit second timestamp since epoch 2014-05-13T16:53:20Z + 128-bit payload across 27 base62 characters. Snowflakes decode through the shared snowflake decoder library with platform epochs. Collision estimates use the birthday bound p ≈ 1 − e^(−n(n−1)/2·2^bits). Verified against the ULID spec example, the segmentio/ksuid README example, and ulid npm round-trips. ## Inputs - **IDs (one per line)** (textarea): 01ARZ3NDEKTSV4RRFFQ69G5FAV 0ujtsYcgvSTl8PAuAdqWYSMnLOv 175928847299117063 - **Format** (select) - **Collision estimate (IDs generated)** (number): Number of IDs assumed generated inside one time window when estimating collision probability. ## When to use - Identify an unfamiliar ID format and inspect its encoded fields. - Extract creation timestamps from ULIDs, KSUIDs, ObjectIds, or supported Snowflake IDs. - Estimate collision probability for generated IDs using a specified count. ## How it works - Paste one or more IDs into the IDs field, with one ID on each line. - Choose Auto-detect or pin the format to ULID, KSUID, NanoID, ObjectId, or a supported Snowflake type. - The decoder analyzes each ID with BigInt-based parsing and shows format-specific fields such as timestamps, randomness, payloads, or Snowflake bit segments. - Set Collision estimate (IDs generated) to calculate a birthday-bound collision estimate for the relevant identifier space. ## Use cases - Debug ID generation by verifying timestamps, hexadecimal values, and encoded bit fields. - Investigate records and events by recovering time information from sortable IDs. - Compare identifier designs by reviewing entropy and estimated collision resistance. ## Frequently asked questions ### Which ID formats can this decoder analyze? It supports ULID, KSUID, NanoID, MongoDB ObjectId, and Discord, Twitter, and Sonyflake Snowflake IDs. ### Can I decode multiple IDs at once? Yes. Enter one ID per line in the IDs field. ### Does a NanoID contain a timestamp? No. NanoID has no timestamp component, so the tool reports its URL-safe alphabet and entropy instead. ### Which Snowflake format should I select? Select Discord, Twitter, or Sonyflake according to the system that generated the ID. Auto-detection may identify the numeric form, but the platform epoch matters for timestamp decoding. ### How is collision probability estimated? The tool uses a birthday-bound approximation based on the number of generated IDs and the available random or payload bits. ## Related tools - [NTP RFC 5905 / SNTP Leap Second & Epoch Decoder](https://elysiatools.com/en/tools/ntp-rfc-5905-sntp-leap-second-epoch-decoder): Decode an NTP/SNTP 48-byte packet: LI/VN/Mode bitfield, stratum, poll, precision, root delay/dispersion, reference ID (with clock & kiss codes), and four 64-bit 1900-epoch timestamps - [Snowflake / Discord ID Bit Decoder](https://elysiatools.com/en/tools/snowflake-discord-id-bit-decoder): Decode 64-bit Snowflake-style IDs for Discord, Twitter, Mastodon, Sonyflake, Instagram, or a custom bit profile. Extract timestamp, worker/process/machine, sequence fields, align platform epochs, and infer a Discord shard when a shard count is supplied. - [Modern Unique ID Generator](https://elysiatools.com/en/tools/uid-generator): Generate modern unique identifiers: ULID, NanoID, Snowflake and CUID2. 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