JSON for Modern C++ vs SwiftyJSON
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
Open source · MIT
A single-header C++ library for reading, writing and manipulating JSON data.
Open source · MIT
A Swift library that makes reading JSON data simpler and safer than Foundation's built-in parsing.
The short answer
Choose JSON for Modern C++ if you need…
- C++ developers who need to read or write JSON in an application
- Teams that want a library with no dependencies and a simple header-based setup
- Projects that prioritize ease of use over raw parsing speed
- Developers who want JSON Patch or JSON Pointer support in C++
Choose SwiftyJSON if you need…
- Swift developers building iOS, macOS, tvOS or watchOS apps that read JSON from web APIs
- Teams maintaining existing projects that already use SwiftyJSON
- Developers who want quick access to nested JSON without writing many optional casts
Side-by-side
| JSON for Modern C++ | SwiftyJSON | |
|---|---|---|
| Type | Library | Library |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 50.8k | 22.9k |
| Setup difficulty | Beginner | Beginner |
| How you get it | Clone and build from source | Install with a package manager |
| Main language | C++ | Swift |
| Last code update | 4 days ago | 3 months ago |
What each one is
JSON for Modern C++
nlohmann/json is a C++ library that lets programs work with JSON data using familiar C++ containers and operators, so JSON objects and arrays can be handled much like std::map and std::vector. It is distributed as a single header file, which makes it simple to add to a project. The README also mentions support for related formats such as CBOR, MessagePack and BSON, plus JSON Pointer and JSON Patch.
SwiftyJSON
SwiftyJSON is a Swift library for working with JSON data, the common text format apps use to exchange information with servers. Instead of writing nested type casts to pull out a value, you can write short paths like json[0]["user"]["name"] and get an optional or a default value back. The README says this avoids crashes from missing keys or wrong types, because errors are stored on the result rather than thrown.
Best for
JSON for Modern C++
- C++ developers who need to read or write JSON in an application
- Teams that want a library with no dependencies and a simple header-based setup
- Projects that prioritize ease of use over raw parsing speed
- Developers who want JSON Patch or JSON Pointer support in C++
SwiftyJSON
- Swift developers building iOS, macOS, tvOS or watchOS apps that read JSON from web APIs
- Teams maintaining existing projects that already use SwiftyJSON
- Developers who want quick access to nested JSON without writing many optional casts
Strengths
JSON for Modern C++
- Single header file with no dependencies, according to the README
- Intuitive syntax that feels close to native C++ containers
- Heavily unit-tested with fuzzing via Google OSS-Fuzz and MIT licensed
SwiftyJSON
- Short, readable syntax for nested JSON access compared with the README's JSONSerialization examples
- Missing keys or wrong types return an error value instead of crashing, according to the README
- Supports common installation routes: CocoaPods, Carthage and Swift Package Manager
Not ideal for
JSON for Modern C++
- Projects that need the fastest possible JSON parsing, since the README says faster libraries exist
- Developers not working in C++, because this library is for C++ only
- Projects that must avoid a large single header file in build times, as the README does not discuss compile-time cost
SwiftyJSON
- Projects that need strongly typed models; the README's approach is dynamic lookup, and Swift's Codable is not discussed in the README excerpt
- Non-Swift projects, since this is a Swift library
- Projects on platform versions or Swift toolchains below those listed in the Requirements section
Trade-offs
JSON for Modern C++
- The README says it is not the fastest JSON library available
- Documentation and examples are primarily hosted on an external site, so the README alone gives limited detail
- The README is truncated, so some features and setup details could not be verified here
SwiftyJSON
- Dynamic lookups move type checking to runtime, so typos in keys are caught later than with typed models
- The README excerpt is truncated, so details of the newer 5.x API are not fully visible here
- Latest release shown is 5.0.2 with no binaries, so you install it through a package manager or source
Getting started
JSON for Modern C++
Clone the repository
git clone https://github.com/nlohmann/json.gitSwiftyJSON
Add to Package.swift (Swift Package Manager)
https://github.com/SwiftyJSON/SwiftyJSON.gitInstall with CocoaPods (Podfile entry)
pod 'SwiftyJSON', '~> 4.0'Frequently asked questions
What is the difference between JSON for Modern C++ and SwiftyJSON?
JSON for Modern C++: A single-header C++ library for reading, writing and manipulating JSON data. SwiftyJSON: A Swift library that makes reading JSON data simpler and safer than Foundation's built-in parsing. JSON for Modern C++ suits c++ developers who need to read or write json in an application, while SwiftyJSON suits swift developers building ios, macos, tvos or watchos apps that read json from web apis.
Are JSON for Modern C++ and SwiftyJSON free?
JSON for Modern C++: Free and open source. SwiftyJSON: Free and open source.
Is JSON for Modern C++ or SwiftyJSON more popular?
JSON for Modern C++ has more GitHub stars (50.8k) than SwiftyJSON (22.9k). Popularity isn't the same as fit — check which one matches your use case above.
What are other alternatives to JSON for Modern C++ and SwiftyJSON?
Other options people compare them with include GJSON, cpp-httplib, EnTT, Alamofire, SwifterSwift.
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.