Pros of msquic

• More active development with frequent updates and contributions
• Extensive documentation and examples for easier implementation
• Cross-platform support for Windows, Linux, and macOS

Cons of msquic

• Larger codebase, potentially more complex to understand and maintain
• Primarily focused on Windows ecosystem, which may not be ideal for all use cases
• Steeper learning curve for developers not familiar with Microsoft technologies

Code Comparison

msquic:

QUIC_STATUS
QUIC_API
MsQuicOpenVersion(
    _In_ uint32_t Version,
    _Out_ _Pre_defensive_ const QUIC_API_TABLE** QuicApi
    )

lsquic:

int
lsquic_engine_init (const struct lsquic_engine_settings *,
                    unsigned flags);

The code snippets show different initialization approaches. msquic uses a version-based API initialization, while lsquic uses a simpler engine initialization with settings and flags.

Both libraries provide QUIC protocol implementation, but msquic offers broader platform support and more extensive documentation. lsquic may be simpler to integrate for certain projects, especially those not tied to the Microsoft ecosystem. The choice between them depends on specific project requirements and target platforms.

Pros of aioquic

• Written in pure Python, making it more accessible and easier to integrate with Python projects
• Supports both client and server implementations of QUIC and HTTP/3
• Designed to work seamlessly with asyncio, providing non-blocking I/O operations

Cons of aioquic

• May have lower performance compared to lsquic, which is written in C
• Less mature and potentially less battle-tested than lsquic
• Limited platform support compared to lsquic's broader compatibility

Code Comparison

aioquic example:

async def run_client(configuration: QuicConfiguration):
    async with connect("localhost", 4433, configuration=configuration) as client:
        await client.ping()

lsquic example:

static int
http_client_on_write(struct lsquic_stream *stream, lsquic_stream_ctx_t *st_h)
{
    struct http_client_ctx *const ctx = (void *) st_h;
    return send_headers(stream, ctx);
}

Both libraries provide APIs for QUIC functionality, but aioquic offers a more Pythonic interface with async/await syntax, while lsquic uses a C-style callback approach. The aioquic example demonstrates a simple client connection, while the lsquic example shows a write callback function for an HTTP client.

Pros of ngtcp2

• More actively maintained with frequent updates
• Broader focus on QUIC protocol implementation, not just limited to HTTP/3
• Extensive test suite and documentation

Cons of ngtcp2

• Steeper learning curve due to its lower-level implementation
• May require more integration work for specific use cases
• Less optimized for production environments out of the box

Code Comparison

ngtcp2:

ngtcp2_conn *conn;
ngtcp2_conn_client_new(&conn, dcid, &params, &callbacks, NULL);
ngtcp2_conn_handshake(conn, buf, &pktlen, NULL, 0, timestamp);

lsquic:

lsquic_engine_t *engine;
lsquic_engine_new(LSENG_SERVER, &engine_api);
lsquic_engine_connect(engine, version, local_sa, peer_sa, NULL, ssl_ctx, NULL, 0, NULL, 0, NULL, 0);

Summary

ngtcp2 offers a more comprehensive QUIC implementation with active development and extensive testing. It's suitable for projects requiring fine-grained control over the QUIC protocol. However, it may require more effort to integrate and optimize for specific use cases.

lsquic, developed by LiteSpeed Technologies, is more focused on HTTP/3 and optimized for production environments. It provides an easier integration path but may be less flexible for non-HTTP/3 QUIC applications.

Choose ngtcp2 for broader QUIC protocol support and active development, or lsquic for a more production-ready HTTP/3 implementation with easier integration.

Pros of quic-go

• Written in Go, offering better cross-platform compatibility and easier integration with Go-based projects
• More active community and frequent updates, potentially leading to faster bug fixes and feature additions
• Extensive documentation and examples, making it easier for developers to get started and implement QUIC

Cons of quic-go

• May have slightly lower performance compared to lsquic, which is written in C
• Less mature and battle-tested in production environments compared to lsquic
• Potentially higher memory usage due to Go's garbage collection

Code Comparison

lsquic (C):

lsquic_conn_t *conn = lsquic_engine_connect(engine, version, &local_sa, &peer_sa,
                                            (void *) peer_ctx, ssl_ctx,
                                            NULL, 0, NULL, 0, NULL, 0);

quic-go (Go):

session, err := quic.DialAddr(addr, tlsConf, config)
if err != nil {
    return nil, err
}

The code snippets demonstrate the difference in connection establishment between the two libraries. lsquic requires more parameters and configuration, while quic-go offers a more straightforward API. This reflects the general design philosophy of each library, with quic-go prioritizing ease of use and lsquic focusing on fine-grained control and performance.