AI · alternatives · 2026

24 alternatives to Incremental JSON parser for streaming LLM tool calls in Ruby

Built this for streaming AI tool calls. LLMs stream function arguments as JSON character-by-character. Most parsers reparse from scratch each time - O(n²) behavior that causes UI lag. This maintains parsing state, processing only new characters. True O(n) performance that stays imperceptible throughout the entire response. Ruby gem, MIT licensed. Would love feedback.

This Ruby gem parses JSON incrementally as it arrives character-by-character from streaming language models, avoiding the performance bottleneck of reparsing entire documents. Instead of O(n²) complexity that causes UI… Below are 24 products that do a similar job, ranked by how close each is in meaning and then by launch-day votes.

1
LLMs can generate valid JSON 100% of the time▲854
Outlines is a Python library that focuses on text generation with large language models. Brandon and I are not LLM experts and started the project a few months ago because we wanted to understand better how the generation process works. Our original background is probabilistic, relational and symbolic programming. Recently we came up with a fast way to generate text that matches a regex (https://blog.normalcomputing.ai/posts/2023-07-27-regex-guide...). The basic idea is simple: regular expressions have an equivalent Deterministic-Finite Automaton (DFA) representation. We…
2023 · github.com · its alternatives →
2
Beyond text splitting – improved file parsing for LLMs▲206
Improved file parsing for LLM’s. Contribute to Filimoa/open-parse development by creating an account on GitHub.
2024 · github.com · its alternatives →
3
A Fast, Malloc-Free C++14 Json Parser and Encoder▲98
Meta programming utilities for C++14. Merged in matt-42/lithium - matt-42/iod
2014 · github.com · its alternatives →
4
jql – Easier jq Alternative with a Lispy Syntax Written in Go▲217
Easy JSON Query Processor with a Lispy syntax in Go - cube2222/jql
2020 · github.com · its alternatives →
5
Agents.json – OpenAPI Specification for LLMs▲212
Hey HN, we’re building an open specification that lets agents discover and invoke APIs with natural language, built on the OpenAPI standard. agents.json clearly defines the contract between LLMs and API as a standard that's open, observable, and replicable. Here’s a walkthrough of how it works: https://youtu.be/kby2Wdt2Dtk?si=59xGCDy48Zzwr7ND. There’s 2 parts to this: 1. An agents.json file describes how to link API calls together into outcome-based tools for LLMs. This file sits alongside an OpenAPI file. 2. The agents.json SDK loads agents.json files as tools for an LLM that…
2025 · github.com · its alternatives →
6
Robust LLM extractor for websites in TypeScript▲72
We've been building data pipelines that scrape websites and extract structured data for a while now. If you've done this, you know the drill: you write CSS selectors, the site changes its layout, everything breaks at 2am, and you spend your morning rewriting parsers. LLMs seemed like the obvious fix — just throw the HTML at GPT and ask for JSON. Except in practice, it's more painful than that: - Raw HTML is full of nav bars, footers, and tracking junk that eats your token budget. A typical product page is 80% noise. - LLMs return malformed JSON more often than you'd expect, especially with…
Mar 2026 · github.com · its alternatives →
7
Very low footprint JSON parser in portable ANSI C▲111
Very low footprint DOM-style JSON parser written in portable ANSI C - json-parser/json-parser
2012 · github.com · its alternatives →
8
A fast JSON library for Go▲119
Fast JSON encoder/decoder compatible with encoding/json for Go - goccy/go-json
2021 · github.com · its alternatives →
9
Python JSON library in Rust, faster than ujson▲40
Fast, correct Python JSON library supporting dataclasses, datetimes, and numpy - ijl/orjson
2018 · github.com · its alternatives →
10
ffjson: faster json serialization in Go▲83
2014 · journal.paul.querna.org · its alternatives →
11
uDSV.js – A faster CSV parser▲67
Hey folks! I know CSV parsers (especially in JS) aren't terribly exciting and someone writes a "better" one every week. I'm in the middle of my parental leave, and this was a project that came out of me looking for the fastest/smallest CSV parser. It all started so innocently, and then turned into a benchmark-validation-athon; the library itself took ~2 weeks to write, but the performance comparisons took another ~4 weeks (on and off). The benchmarks were a huge effort, but I think they are the most thorough to date, both in breadth and in depth, so hopefully you find them useful:…
2023 · github.com · its alternatives →
12
Jsong: faster than light streaming JSON parser and writer in C▲9
2017 · github.com · its alternatives →
13
Feedsmith — Fast parser & generator for RSS, Atom, OPML feed namespaces▲70
Hi HN! While working on a project that involves frequently parsing a lot of feeds, I needed a fast JavaScript-based parser to extract specific fields from feed namespaces. Existing Node packages were either too slow or merged all feed formats, losing namespace information. So I decided to write it myself and created this NPM package with a simple API. Feedsmith supports all feed formats and many popular namespaces, including: Podcast, Media, iTunes, Dublin Core, and more. It can also parse and generate OPML files. I am currently adding support for more namespaces and feed generation for RSS,…
2025 · github.com · its alternatives →
14
Streaming JSON in Rust▲7
Terabytes of JSON, kilobytes of memory
Jan 2026 · github.com · its alternatives →
15
Weird JSON superset with BigInt, Infinity, TypedArray etc▲67
the JS/Node.JS library for encoding complex and unconventional data structures. Support for BigInts, TypedArrays, null, undefined, and Symbol. Multiple flavors available. - DO-SAY-GO/WeirdJSON
2020 · github.com · its alternatives →
16AT
Anything To JSON – a language model for structured extraction▲18
Hey HN! Erik here from banana.dev We’ve trained a small(ish) language model on structured extraction, and today we’re launching a playground for it at https://anythingtojson.com. Give it a try! This model continues our work on structured generation, following last week’s launch of Fructose[1], a python client for strongly-typed LLM responses. There seem to be two distinct halves of the problem intended to be solved by Fructose and structured generation: 1. the reasoning ability of the model, such as performing chain of thought, creative acts, and natural language tasks. In a way,…
2024 · anythingtojson.com · its alternatives →
17
A new benchmark for testing LLMs for deterministic outputs▲60
When building workflows that rely on LLMs, we commonly use structured output for programmatic use cases like converting an invoice into rows or meeting transcripts into tickets or even complex PDFs into database entries. The model may return the schema you want, but with hallucinated values like `invoice_date` being off by 2 months or the transcript array ordered wrongly. The JSON is valid, but the values are not. Structured output today is a big part of using LLMs, especially when building deterministic workflows. Current structured output benchmarks (e.g., JSONSchemaBench) only validate…
Apr 2026 · interfaze.ai · its alternatives →
18AT
A tool to benchmark LLM APIs (OpenAI, Claude, local/self-hosted)▲55
I recently built a small open-source tool to benchmark different LLM API endpoints — including OpenAI, Claude, and self-hosted models (like llama.cpp). It runs a configurable number of test requests and reports two key metrics: • First-token latency (ms): How long it takes for the first token to appear • Output speed (tokens/sec): Overall output fluency Demo: https://llmapitest.com/ Code: https://github.com/qjr87/llm-api-test The goal is to provide a simple, visual, and reproducible way to evaluate performance across different LLM providers, including…
2025 · llmapitest.com · its alternatives →
19
fastjson - Fast JSON Parsing for Go▲20
Fast JSON parser and validator for Go. No custom structs, no code generation, no reflection - valyala/fastjson
2018 · github.com · its alternatives →
20
Json-knife (update huge JSON string recursively with regex)▲6
An Experimental Regex Engine to Parse and Apply Bulk Changes to a JSON String Without Using 'JSON.parse()' for Deserialization - patternhelloworld/json-knife
2020 · github.com · its alternatives →
21
Visualising how streaming AJAX speeds up the web▲13
A streaming approach to JSON. Oboe.js is a Javascript library for Node.js and browsers that speeds up web applications by providing parsed objects before the response completes
2014 · oboejs.com · its alternatives →
22
A lightweight JSON Parser without memory allocation in ~250 LOC▲9
2014 · github.com · its alternatives →
23
An LLM response cache that's aware of dynamic data▲17
Raymond here from Butter.dev, an LLM response cache built as a chat-completions proxy. Today we're launching a key feature for the platform: the ability to generalize on dynamic, templated inputs. Caching at the HTTP request level has the obvious problem of generalizability. Nearly no request is identical, due to templated variables (like names) and metadata (like timestamps), so exact-match cache lookups rarely hit. We solve this at Butter by using LLMs to detect dynamic content in requests and derive their inter-relationships, allowing the cache entry to be stored as a template + variables…
Jan 2026 · blog.butter.dev · its alternatives →
24
bote - A fast, modern and low-memory approach to processing a big JSON▲5
A fast, modern and low-memory approach to processing a big JSON - jankdc/bote
Jun 2026 · github.com · its alternatives →

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