mkid

A tiny Rust-based CLI tool to generate unique IDs, primarily UUIDs. Built as a more capable alternative to uuidgen, with support for all UUID versions (v1-v8), multiple output formats, and clipboard integration.

Features

• Quick shortcuts: mkid4 and mkid7 for instant UUID generation
• All UUID versions supported: v1 through v8
• Smart defaults: mkid generates UUID v7 (sortable, database-friendly)
• Multiple formats: hyphenated, simple, URN, braced
• Case control: lowercase (default) or uppercase
• Clipboard integration: Copy output directly to clipboard
• Bulk generation: Generate multiple UUIDs at once
• Fast and lightweight: Three small binaries, minimal dependencies

Installation

With cargo-binstall (recommended)

The fastest way to install pre-built binaries:

cargo binstall mkid

From GitHub releases

Download pre-built binaries directly from GitHub releases.

From crates.io

Build from source via crates.io:

cargo install mkid --locked

From source

Build from the repository:

git clone https://github.com/asaaki/mkid
cd mkid
cargo install --path .

Usage

Quick Shortcuts

For maximum convenience, use the shortcut commands:

# UUID v4 (random) - fastest way
mkid4
# Output: 18431fda-68f1-42af-9318-1ece3d60281e

# UUID v7 (sortable) - fastest way
mkid7
# Output: 019c1064-a92c-74f0-98d9-03496f8a9693

Basic Usage

Generate a UUID v7 (default):

mkid
# Output: 019c0edc-d74c-7c02-beb9-40fcf2eee5f6

UUID Versions

Generate specific UUID versions:

# UUID v4 (random)
mkid uuid v4

# UUID v7 (timestamp-based, sortable)
mkid uuid v7

# UUID v1 (time-based with node ID)
mkid uuid v1 --random-node

# UUID v3 (MD5 hash-based)
mkid uuid v3 --namespace dns --name example.com

# UUID v5 (SHA-1 hash-based)
mkid uuid v5 --namespace url --name https://example.com

# UUID v6 (sortable time-based)
mkid uuid v6 --random-node

# UUID v8 (custom)
mkid uuid v8 --bytes 0123456789abcdef0123456789abcdef

Version-Specific Options

For v1/v6 (time-based):

• --random-node: Use random 6-byte node ID (default)
• --node-id <HEX>: Specify custom node ID (12 hex characters)

mkid uuid v1 --node-id aabbccddeeff

For v3/v5 (hash-based):

• --namespace <NS>: Namespace (dns, url, oid, x500, or custom UUID)
• --name <NAME>: Name to hash (required)

mkid uuid v5 --namespace dns --name example.com
# Output is deterministic: same namespace + name = same UUID

For v8 (custom):

• --bytes <HEX>: 32 hex characters (16 bytes)

mkid uuid v8 --bytes 0123456789abcdef0123456789abcdef

Output Formats

# Hyphenated (default)
mkid uuid v7 --format hyphenated
# 019c0edc-d74c-7c02-beb9-40fcf2eee5f6

# Simple (no hyphens)
mkid uuid v7 --format simple
# 019c0edcd74c7c02beb940fcf2eee5f6

# URN
mkid uuid v7 --format urn
# urn:uuid:019c0edc-d74c-7c02-beb9-40fcf2eee5f6

# Braced
mkid uuid v7 --format braced
# {019c0edc-d74c-7c02-beb9-40fcf2eee5f6}

Case Control

# Uppercase
mkid uuid v7 --uppercase
# 019C0EDC-D74C-7C02-BEB9-40FCF2EEE5F6

# Lowercase (default)
mkid uuid v7
# 019c0edc-d74c-7c02-beb9-40fcf2eee5f6

Bulk Generation

# Generate 5 UUIDs
mkid uuid v7 --count 5
# 019c0edd-19ee-7903-8ec0-cc2098967b15
# 019c0edd-19ee-7903-8ec0-cc324e67abd2
# 019c0edd-19ee-7903-8ec0-cc4871c57653
# 019c0edd-19ee-7903-8ec0-cc552b063bff
# 019c0edd-19ee-7903-8ec0-cc6150da757c

Note: v7 UUIDs are monotonic (sortable by generation time).

Clipboard Integration

# Copy to clipboard
mkid --clipboard
mkid uuid v7 --clipboard

# Copy multiple UUIDs (newline-separated)
mkid uuid v4 --count 5 --clipboard

Combining Options

# Multiple options at once
mkid uuid v7 --uppercase --format simple --count 3 --clipboard
# 019C0EDD08B37C42AABE599AEA317DE1
# 019C0EDD08B37C42AABE599D2F5B8A92
# 019C0EDD08B37C42AABE599E5C9A1B23
# (also copied to clipboard)

Why UUID v7?

UUID v7 is the default because it provides:

1. Database performance: Time-ordered UUIDs reduce B-tree fragmentation (up to 10x better than v4)
2. Sortability: Lexicographic comparison works directly on the UUID bytes
3. Modern timestamps: Uses Unix epoch in milliseconds (familiar to developers)
4. Monotonicity: Sequential UUIDs are guaranteed to be ordered
5. No clock drift issues: Better than v1/v6 for distributed systems

UUID Version Comparison

Version	Type	Use Case	Deterministic
v1	Time + Node	Legacy systems	No
v3	MD5 hash	Namespace-based (legacy)	Yes
v4	Random	General purpose	No
v5	SHA-1 hash	Namespace-based	Yes
v6	Sortable time	Database keys (modern)	No
v7	Timestamp	Database keys (recommended)	No
v8	Custom	Special requirements	Depends

Examples

Generate API keys

mkid uuid v4 --format simple --uppercase

Generate sortable database IDs

mkid uuid v7 --count 100

Generate deterministic UUIDs for testing

mkid uuid v5 --namespace dns --name test-user-1
mkid uuid v5 --namespace dns --name test-user-2

Quick clipboard workflow

mkid -c  # Generate v7 and copy to clipboard
# Paste anywhere: Cmd+V (macOS) or Ctrl+V (Linux/Windows)

Testing

Run the test suite:

cargo test

The project includes comprehensive integration tests covering:

• All UUID versions
• Format options
• Deterministic behavior (v3/v5)
• Monotonicity (v7)
• Error handling
• Count functionality

Future Plans

The architecture supports future addition of other ID formats:

• ULID (Universally Unique Lexicographically Sortable Identifier)
• NanoID (URL-friendly unique ID)
• Snowflake (Twitter's distributed ID)
• CUID (Collision-resistant Unique ID)

Example future usage:

mkid ulid
mkid nanoid
mkid snowflake

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contributing

Contributions welcome! Please feel free to submit a Pull Request.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.