Sqids (pronounced "squids") is a small library that lets you generate unique IDs from numbers. It's good for link shortening, fast & URL-safe ID generation and decoding back into numbers for quicker database lookups.

Features:

• Encode multiple numbers - generate short IDs from one or several non-negative numbers
• Quick decoding - easily decode IDs back into numbers
• Unique IDs - generate unique IDs by shuffling the alphabet once
• ID padding - provide minimum length to make IDs more uniform
• URL safe - auto-generated IDs do not contain common profanity
• Randomized output - Sequential input provides nonconsecutive IDs
• Many implementations - Support for 40+ programming languages

Good for:

• Generating IDs for public URLs (eg: link shortening)
• Generating IDs for internal systems (eg: event tracking)
• Decoding for quicker database lookups (eg: by primary keys)

Not good for:

• Sensitive data (this is not an encryption library)
• User IDs (can be decoded revealing user count)

Java 8 or higher is required.

Import dependency. If you are using Apache Maven, add the following dependency to your pom.xml's dependencies:

<dependency>
  <groupId>org.sqids</groupId>
  <artifactId>sqids</artifactId>
  <version>0.1.0</version>
</dependency>

Alternatively, if you use Gradle or are on Android, add the following to your app's build.gradle file under dependencies:

implementation 'org.sqids:sqids:0.1.0'

Import Sqids via:

import org.sqids.Sqids;

Simple encode & decode:

Sqids sqids=Sqids.builder().build();
String id=sqids.encode(Arrays.asList(1L,2L,3L)); // "86Rf07"
List<Long> numbers=sqids.decode(id); // [1, 2, 3]

Note 🚧 Because of the algorithm's design, multiple IDs can decode back into the same sequence of numbers. If it's important to your design that IDs are canonical, you have to manually re-encode decoded numbers and check that the generated ID matches.

Enforce a minimum length for IDs:

Sqids sqids=Sqids.builder()
        .minLength(10)
        .build();
String id=sqids.encode(Arrays.asList(1L,2L,3L)); // "86Rf07xd4z"
List<Long> numbers=sqids.decode(id); // [1, 2, 3]

Randomize IDs by providing a custom alphabet:

Sqids sqids=Sqids.builder()
        .alphabet("FxnXM1kBN6cuhsAvjW3Co7l2RePyY8DwaU04Tzt9fHQrqSVKdpimLGIJOgb5ZE")
        .build();
String id=sqids.encode(Arrays.asList(1L,2L,3L)); // "B4aajs"
List<Long> numbers=sqids.decode(id); // [1, 2, 3]

Prevent specific words from appearing anywhere in the auto-generated IDs:

Sqids sqids=Sqids.builder()
        .blockList(new HashSet<>(Arrays.asList("86Rf07")))
        .build();
String id=sqids.encode(Arrays.asList(1L,2L,3L)); // "se8ojk"
List<Long> numbers=sqids.decode(id); // [1, 2, 3]

MIT