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.

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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.

Details

What this tool helps you do

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.

Execution

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Prepared example runs

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2 examples

Decode one ULID, one KSUID and one snowflake integer together

Three pasted IDs from different systems — a 26-character ULID, the 27-character KSUID from the segmentio README and a 64-bit Snowflake-style integer — are auto-detected and decoded with timestamps and bit-level field breakdowns; the numeric ID is decoded with the classic Twitter epoch and carries a note to pin Discord/Sonyflake when applicable.

<section>ULID → 2016-07-30T23:54:10.259Z (80-bit randomness) · KSUID → 2017-10-10T04:00:47.000Z · snowflake-twitter → 2012-03-03T13:01:20.453Z · collision table at n=1,000,000</section>

Pin the format to NanoID and check its entropy

A default 21-character NanoID has no timestamp to recover, so the decoder instead validates the url-safe alphabet, reports 126 bits of entropy and its UUID v4-level collision resistance.

<section>NanoID · url-safe alphabet · entropy 126 bits · UUID v4-level collision resistance · no timestamp component</section>

Inputs

Set the required fields, then run the tool.

3 options

ContentPaste or type the main input values.1

IDs (one per line)textareaRequired

SettingsAdjust formats, ranges, numbers, and modes.2

FormatselectOptionalCollision estimate (IDs generated)numberOptionalNumber of IDs assumed generated inside one time window when estimating collision probability.

Result

Ready for a run

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Samples

ULID / NanoID / KSUID / Snowflake ID Decoder

What this tool helps you do

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Inputs

Result

Examples that match this tool

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Inputs

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Key facts

Overview

When to use

How it works

Use cases

Examples

1. Decode mixed sortable IDs

2. Inspect NanoID entropy

FAQ

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3. Check a platform Snowflake timestamp