teletype-crdt VS diamond-types

Compare teletype-crdt vs diamond-types and see what are their differences.


String-wise sequence CRDT powering peer-to-peer collaborative editing in Teletype for Atom. (by atom)


The world's fastest CRDT. WIP. (by josephg)
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teletype-crdt diamond-types
3 8
710 657
1.3% -
0.0 9.7
about 2 months ago 11 days ago
JavaScript Rust
MIT License -
The number of mentions indicates the total number of mentions that we've tracked plus the number of user suggested alternatives.
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.


Posts with mentions or reviews of teletype-crdt. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2021-07-31.
  • Teletype: String-wise sequence CRDT powering peer-to-peer collaborative editing
    1 project | | 23 Apr 2022
  • 5000x Faster CRDTs: An Adventure in Optimization
    8 projects | | 31 Jul 2021
    Cool! It'd be interesting to see those CRDT implementations added to Kevin Jahns' CRDT Benchmarks page[1]. The LogootSplit paper looks interesting. It looks like xray is abandoned, and I'm not sure about teletype. Though teletype's CRDT looks to be entirely implemented in javascript[2]? If the authors are around I'd love to see some benchmarks so we can compare approaches and learn what actually works well.

    And I'm not surprised these techniques have been invented before. Realising a tree is an appropriate data structure here is a pretty obvious step if you have a mind for data structures.

    To name it, I often find myself feeling defensive when people read my work and respond with a bunch of links to academic papers. Its probably totally unfair and a complete projection from my side, but I hear a voice in my head reword your comment to instead say something awful like: "Cool, but everything you did was done before. Even if they didn't make any of their work practical, usable or good they still published first and you obviously didn't do a good enough literature review if you didn't know that." And I feel an unfair defensiveness arise in me as a result that wants to find excuses to dismiss the work, even if the work might be otherwise interesting.

    Its hard to compare their benchmark results because they used synthetic randomized editing traces, which always have different performance profiles than real edits for this stuff. Their own university gathered some great real world data in an earlier study. It would have been much more instructive if that data set was used here. At a glance their RAM usage looks to be about 2 orders of magnitude worse than diamond-types or yjs. And their CPU usage... ?? I can't tell because they have no tables of results. Just some hard to read charts with log scales, so you can't even really eyeball the figures. So its really hard to tell if their work ends up performance-competitive without spending a couple days getting their enterprise style java code running with a better data set. Do you think thats worth doing?



  • Atom Teletype's peer-to-peer connection
    5 projects | | 28 Mar 2021
    1) crdt


Posts with mentions or reviews of diamond-types. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2022-04-19.
  • WebAssembly 2.0 Working Draft
    21 projects | | 19 Apr 2022
    > In this case, the bottleneck at 9 million LoC is not CPU cycles but memory usage. That's where I am considering pushing down into WebAssembly

    How often does this come up in practice? I can't think of many files I've opened which were 9 million lines long. And you say "LoC" (lines of code). Are you doing syntax highlighting on 9 million lines of source code in javascript? Thats impressive!

    > I guess my point is why do you need balanced trees? Is this a CRDT specific thing? Can you implement CRDT with just an array of lines / gap buffer?

    Of course! Its just going to be slower. I made a simple reference implementation of Yjs, Automerge and Sync9's list types in javascript here[1]. This code is not optimized, and it takes 30 seconds to process an editing trace that diamond types (in native rust) takes 0.01 seconds to process. We could speed that up - yjs does the same thing in 1 second. But I don't think javascript will ever run as fast as optimized rust code.

    The b-tree in diamond types is used for merging. If you're merging 2 branches, we need to map insert locations from the incoming branch into positions in the target (merged) branch. As items are inserted, the mapping changes dynamically. The benchmark I've been using for this is how long it takes to replay (and re-merge) all the changes in the most edited file in the nodejs git repository. That file has just shy of 1M single character insert / delete operations. If you're curious, the causal graph of changes looks like this[2].

    Currently it takes 250ms to re-merge the entire causal graph. This is much slower than I'd like, but we can cache the merged positions in about 4kb on disk or something so we only need to do it once. I also want to replace the b-tree with a skip list. I think that'll make the code faster and smaller.

    A gap buffer in javascript might work ok... if you're keen, I'd love to see that benchmark. The code to port is here: [3]

    > Undo support -> In which case, you only have to stack / remember the set of commands and not have to store the state on every change. I'm not sure if this overlaps with the data structure choice, other than implementation details.

    Yeah, I basically never store a snapshot of the state. Not on every change. Not really at all. Everything involves sending around patches. But you can't just roll back the changes when you undo.

    Eg: I type "aaa" at position 0 (the start of the document). You type "bbb" at the start of the document. The document is now "bbbaaa". I hit undo. What should happen? Surely, we delete the "aaa" - now at position 3.

    Translating from position 0 to position 3 is essentially the same algorithm we need to run in order to merge.

    > I was just looking into TypedArrays.

    I tried optimizing a physics library a few years ago by putting everything in typedarrays and it was weirdly slower than using raw javascript arrays. I have no idea why - but maybe thats fixed now.

    TypedArrays are useful, but they're no panacea. You could probably write a custom b-tree on top of a typedarray in javascript if you really want to - assuming your data also fits into typedarrays. But at that point you may as well just use wasm. It'll be way faster and more ergonomic.




  • I was wrong. CRDTs are the future
    4 projects | | 16 Apr 2022
    Hi everyone! Author here. I'm happy to answer questions.

    I wrote this a couple years ago. Since then I've been working on my own CRDT called Diamond Types[1], which uses a lot of these ideas to be bonkers fast. I've built several OT based collaborative editing systems, and diamond types is much faster than any of them - though rust and wasm might be the real MVPs here. I wrote a follow-up to this article last year when I got that working, talking about how some of the optimizations work. That article is here[2].

    A fair bit has changed since I wrote that article. Yjs has started a rewrite in rust (called yrs[3]). And Automerge has apparently dramatically improved performance based on some of the ideas I talk about in this article. Oh, and diamond types has been rewritten from the ground up. Its now about 5x faster than it was last year, by completely changing the internal structure. But thats a story for another day.

    Unfortunately I still only support collaborative text editing. Adding full JSON support comes soon, after I document some more of the tricks I'm doing. Its really fun work!

    Why do I only support collaborative text editing? Because I care about performance, and text CRDT performance is hard because you have so many individual changes. (One for each keystroke!). Making text editing fast means everything is fast. But we've still got to do the work. To make that happen, my plan is to add full JSON editing support to diamond types using shelf[4]. Shelf is a super simple CRDT which fits in 100 lines of javascript.





  • Conflict-Free Replicated Data Types (CRDT)
    4 projects | | 10 Apr 2022
    Yep. I've done something very similar on top of Diamond Types for a little personal wiki. This page[1] is synced between all users who have the page open. Its a remarkably small piece of code, outside of the CRDT library itself (which is in rust via wasm). The way it works is:

    - On page load, the server sends the whole CRDT document to the browser, and the server streams changes from that point onwards.

    - When a change happens in the browser, it makes that change locally then and sends anything the server doesn't know about upstream.

    - Whenever the server finds out about a new change, it re-broadcasts that change to any subscribed browser streams.

    I'm using the braid HTTP protocol for changes - but we could easily switch to a SSE or websocket solution. It doesn't really matter.

    At the moment I'm just using flat files for storage, but there's nothing stopping you using a database instead, except that its a bit awkward to use efficient CRDT packing techniques in a database.


    Code is here, if anyone is interested. The whole thing is a few hundred lines all up:

  • Writing Redux Reducers in Rust
    3 projects | | 6 Apr 2022
    With each change we just send the missing operations. Https:// if you want to mess around and see it in action via wasm. The code which runs this wiki is here.
  • Investigating Memory Allocations in Rust
    2 projects | | 15 Jan 2022
    Another way to trace allocations in rust is to inject some code in a global allocator. Then you can use any in-program code you like to print / track / trace allocations. For example, I wrote this code in a library Iā€™m working on so I can track and print out how many total bytes have been allocated, and how many allocation calls have been made.
  • What's everyone working on this week (38/2021)?
    8 projects | | 20 Sep 2021
    Working on diamond-types, my high performance CRDT implementation for collaborative editing. I'm trying to get loading and saving working. I'm vaguely lost in all the iterators-of-iterators I have going on. I wish generators were part of the language!
  • 5000x Faster CRDTs: An Adventure in Optimization
    8 projects | | 31 Jul 2021
  • Coding with Character ā€“ Monospaced fonts can be playful and fun
    6 projects | | 27 Jul 2021
    I find that a much more readable style. Instead of stuff on the left - assigned to stuff on the right, its now a story made up of steps: First we're figuring getting some variables for text labels, and distances. Then logging that out. Then after that we're updating the label on the overlay. Each step in the story has a little breath (the newline). And if needed, a comment.

    Here's a random work-in-progress example from some real code I'm working on this week. Its not beautiful or overly fancy. Just steady, confident and readable (assuming you know the context):

What are some alternatives?

When comparing teletype-crdt and diamond-types you can also consider the following projects:

crdt-woot - Implementation of collaborative editing algorithm CRDT WOOT.

automerge - A JSON-like data structure (a CRDT) that can be modified concurrently by different users, and merged again automatically.

crdt-benchmarks - A collection of CRDT benchmarks

comic-shanns - a classy font

Iosevka - Versatile typeface for code, from code.

Hack - A typeface designed for source code

3270font - A 3270 font in a modern format

citrea-model - A CRDT-based collaborative editor engine of (2012, historical)

dotted-logootsplit - A delta-state block-wise sequence CRDT

Selenite - An Experimental Rust Crate for Post-Quantum Code-Signing Certificates.