Alternatives

Products that do what Fetch API compatible, complex form data / JSON body parser and guard does

Hi, We've been working on open sourcing our streaming complex body parser/guard and wouldn't mind some more people contributing. It features: - JSON, urlencoded AND multipart form data parsing - Out-of-the-box constraints for resulting object depth, key amount and size; definable globally and per call, preventing resource exhaustion by bailing on the stream if limits are exceeded - Multi-boundary (!) multipart form data parsing - Multidimensional array form data with auto-increment and explicit indexes (formElement[] vs formElement[0]) - Object form data with dot notation, including…

1. 1
   Parsers▲300

   Extract structured data and visualize it without code

   2019

2. 2LF
   Link.fish – API to extract data from websites as JSON▲201

   2017 · link.fish

3. 3
   Formata▲131

   Secure form endpoints for static sites

   2018

4. 4JM
   JSON5 — modern JSON▲64

   2012 · github.com

5. 5SF
   StaticJSON: fast, direct and static typed parsing of JSON with C++▲18

   2016 · github.com

6. 6SA
   Shunter – a Node.js application to read JSON and translate it into HTML▲33

   2015 · github.com

7. 7CL
   Command-line JSON processing tool▲32

   2018 · github.com

8. 8IB
   I built a CSV parser to try Go 1.26's new SIMD package▲8

   Hey HN, A CSV parser using Go 1.26's experimental simd/archsimd package. I wanted to see what the new SIMD API looks like in practice. CSV parsing is mostly "find these bytes in a buffer"—load 64 bytes, compare, get a bitmask of positions. The interesting part was handling chunk boundaries correctly (quotes and line endings can split across chunks). - Drop-in replacement for encoding/csv - ~20% faster for unquoted data on AVX-512 - Quoted data is slower (still optimizing) - Scalar fallback for non-AVX-512 Requires GOEXPERIMENT=simd.…

   Jan 2026 · github.com

9. 9TF
   The fastest JSON parser for Go▲7

   Jul 2026 · github.com

10. 10SS
    See – searchable JSON compression (offline 10-min demo)▲5

    Hi HN, I’m building SEE (Semantic Entropy Encoding): a searchable compression format for JSON/NDJSON. Goal: reduce the “data tax” (storage/egress) and “CPU tax” (decompress/parse) by keeping JSON searchable while compressed, with page-level random access. I just published a proof-first evaluation release: Offline DEMO ZIP (~10 min): prints compression ratios + skip rates + lookup latency (p50/p95/p99) DD pack: audit/repro evidence (decode mismatch=0, extended mismatch=0, audit PASS) Latest release:…

    Feb 2026 · gitlab.com

11. 11PC
    Parse complex json structures using a simple query syntax▲5

    2016 · github.com

12. 12IH
    Inspect-HTTP-Proxy: a tool to pretty-print JSON requests/responses▲8

    A simple Go-based HTTP proxy designed for detailed inspection of requests and responses. It logs traffic to the console with colorization, automatic decompression, and formatting for common content types, while remaining transparent to the client application. Ideal for debugging API interactions, understanding middleware behavior, or simply getting a clear view of HTTP traffic flow with jq-like pretty-printing & colorization of request/response. Automatically redacts parts of Authorization header to avoid token leakage.

    2025 · github.com

13. 13JI
    Jq-in-the-browser -– jq compatible JSON processor in JavaScript▲15

    2018 · kantord.github.io

14. 14MO
    Minimalist Open Source JSON formatter app▲13

    2020 · jsonformatter.live

15. 15NJ
    Nano-JSON-stream-parser, a 750 bytes streamed JSON parser▲6

    2017 · github.com

16. 16JA
    JSONPlus: a json parser with self reference and templating▲7

    2015 · github.com

17. 17AE
    An easy-to-use go library for parsing and validating form data▲5

    2015 · github.com

18. 18JF
    Jsong: faster than light streaming JSON parser and writer in C▲9

    2017 · github.com

19. 19L0
    Lambda 0.2 – a func language better than TypeScrip, jq and jQuery▲9

    What's your tool chain for data and document processing? - jq is great, but limited to JSON; and jQuery limited to HTML; templating systems get messy for non-trivial logic; TypeScript lacks pattern matching and schema support. So I built Lambda — an expressive functional language that combines the power of Lisp, TypeScript, and many DSLs like jq, jQuery, RelaxNG, etc. It has a lightweight 9 MB runtime, built from scratch in C/C++, that provides an end-to-end document processing pipeline (parse → validate/query/transform → layout → render/view). Internally, Lambda parse…

    Mar 2026 · github.com

20. 20JP
    JSON Parser in C▲7

    A JSON parser in c with some SIMD optimisation for skipping whitespace. The numerical and string parsing functions split out so they are independantly runnable. They were for me the 2 most difficult to understand how they work and to show how the parser was composed of lots of smaller parsers.

    2023 · github.com

21. 21IL
    iZettle/Lift – Swift library for working with JSON-like structures▲8

    2017 · github.com

22. 22JS
    JSON-Safe Lisp Language▲5

    Relatively simple currently, but figured I'd post for some feedback. I started this project last year but somewhat abandoned it. This feels like something which most likely already exists, but I couldn't find anything at the time I made it. I feel like my write up on the repo is pretty good at explaining the inspiration and purpose of this package; "Let's say you have an API, and you're looking for a method by which you can increase performance of your app via doing transformations of the data directly in the API. In this scenario, you would middleman the API returned data through a Fluxduct…

    2022 · github.com

23. 23XS
    xmllm – Structured LLM streaming output using lenient XML parsing▲5

    Hi HN. I made a little JS library for streaming structured data from LLMs using leniently-parsed XML as a medium. E.g. await simple('fun pet names', { schema: { name: Array(String) }, model: 'openrouter:mistralai/ministral-3b' }); // => ["Daisy", "Whiskers", "Rocky"] Demos: xmllm.j11y.io When using LLMs, I've ended up gravitating towards boring time-tested XML-esque tag-based delimiters instead of JSON/function-calling for the following reasons: - Diverse presence in training corpuses (consider flavours of content commonly adjacent to these syntaxes vs. JSON) - HTML was…

    2024 · github.com

24. 24SJ
    Saw.js – live parsing data out of text▲6

    2016 · s.codepen.io

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