0.3

Highlights

Multi-Document Parsing: Read a bundle of JSON documents (ndjson) 2-4x faster than doing it individually. API docs / Design Details
Simplified API: The API has been completely revamped for ease of use, including a new JSON navigation API and fluent support for error code and exception styles of error handling with a single API. Docs
Exact Float Parsing: Now simdjson parses floats flawlessly without any performance loss, thanks to great work by @michaeleisel and @lemire. Blog Post
Even Faster: The fastest parser got faster! With a shiny new UTF-8 validator and meticulously refactored SIMD core, simdjson 0.3 is 15% faster than before, running at 2.5 GB/s (where 0.2 ran at 2.2 GB/s).

Fallback implementation: simdjson now has a non-SIMD fallback implementation, and can run even on very old 64-bit machines.
Automatic allocation: as part of API simplification, the parser no longer has to be preallocated-- it will adjust automatically when it encounters larger files.
Runtime selection API: We've exposed simdjson's runtime CPU detection and implementation selection as an API, so you can tell what implementation we detected and test with other implementations.
Error handling your way: Whether you use exceptions or check error codes, simdjson lets you handle errors in your style. APIs that can fail return simdjson_result, letting you check the error code before using the result. But if you are more comfortable with exceptions, skip the error code and cast straight to T, and exceptions will be thrown automatically if an error happens. Use the same API either way!
Error chaining: We also worked to keep non-exception error-handling short and sweet. Instead of having to check the error code after every single operation, now you can chain JSON navigation calls like looking up an object field or array element, or casting to a string, so that you only have to check the error code once at the very end.