Pkarr Features Reference

Pkarr uses Cargo feature flags to customize functionality for different use cases.

Default Features

With a basic dependency declaration, you get the full-client feature:

[dependencies]
pkarr = "7"

This includes both DHT and relay support, suitable for most server applications.

Base API

Key utilities

Ed25519 key utilities for identity management are always available, including when default features are disabled.

pkarr = { version = "7", default-features = false }

Provides:

• Keypair - Generate and manage Ed25519 keypairs
• PublicKey - Handle public keys and derive z-base32 identifiers

Core Features

signed_packet

DNS packet signing and verification.

pkarr = { version = "7", default-features = false, features = ["signed_packet"] }

Provides:

• SignedPacket - Create and verify signed DNS resource records

Network Features

dht

Direct Mainline DHT access for publishing and resolving records.

pkarr = { version = "7", default-features = false, features = ["dht"] }

Not available in WASM environments.

relays

HTTP relay support for environments without direct DHT access.

pkarr = { version = "7", default-features = false, features = ["relays"] }

Required for WASM/browser applications.

full-client (default)

Both DHT and relay support combined.

pkarr = "7"  # Equivalent to features = ["full-client"]

Extra Features

endpoints

RFC 9460 HTTPS/SVCB service discovery for resolving service endpoints.

This feature enables URLs like https://<pkarr-key> by implementing the full endpoints resolution algorithm. It recursively interprets and resolves SVCB records - when a target points to another Pkarr key, it fetches that packet and continues resolution. Records are sorted by priority for failover and shuffled within priority levels for load balancing.

Returns an async Stream of endpoints. Downstream applications need futures-lite (or equivalent) to consume the stream with .next() and StreamExt.

pkarr = { version = "7", features = ["endpoints"] }

lmdb-cache

Persistent LMDB cache backend for the client.

pkarr = { version = "7", features = ["lmdb-cache"] }

This feature makes pkarr::extra::lmdb_cache::LmdbCache available. It does not change the client's default in-memory cache; create an LmdbCache and pass it to ClientBuilder::cache() to use it.

tls

TLS certificate support for secure connections. Enables endpoints.

pkarr = { version = "7", features = ["tls"] }

reqwest-resolve

Implement reqwest::dns::Resolve trait for the Client. Enables endpoints.

pkarr = { version = "7", features = ["reqwest-resolve"] }

reqwest-builder

Create a reqwest::ClientBuilder from the Pkarr Client. Enables tls and reqwest-resolve.

pkarr = { version = "7", features = ["reqwest-builder"] }

Feature Combinations

extra

All extra features for native client applications. This enables lmdb-cache and reqwest-builder; reqwest-builder enables tls, reqwest-resolve, and endpoints.

pkarr = { version = "7", features = ["extra"] }

full

Everything: full-client + extra.

pkarr = { version = "7", features = ["full"] }

Decision Guide

Use Case	Recommended Features
Server application	full-client (default)
Browser/WASM	relays only
Key handling only	default-features = false
Packet signing only	signed_packet
With persistent cache	lmdb-cache
Service discovery	endpoints
HTTP client integration	reqwest-builder
Everything	full

Platform Compatibility

Feature	Native	WASM
Base key API	Yes	Yes
signed_packet	Yes	Yes
dht	Yes	No
relays	Yes	Yes
lmdb-cache	Yes	No
endpoints	Yes	Yes
tls	Yes	No

Minimal Configurations

Smallest footprint (key utilities only):

pkarr = { version = "7", default-features = false }

WASM browser client:

pkarr = { version = "7", default-features = false, features = ["relays"] }

Server with persistence:

pkarr = { version = "7", features = ["lmdb-cache"] }