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Show HN: Echo – Fable-level results at 1/3 the cost using open-weight models
147 points by adam_rida 3 hours ago | 67 comments

I’ve been building Echo (https://echo.tracerml.ai/), an experiment in making one AI system out of a pool of open-weight models rather than choosing a single model and using it for every task.

It started with a simple experiment. I took a group of models, including GLM-5.2, Kimi K2.7 and others, and ran them on the same evaluations. Then I measured what would happen if, for each problem, you somehow knew in advance which models would be useful and how their outputs should be combined.

That hypothetical system performed substantially better than any individual model in the pool. Of course, it is not something you can actually deploy because it relies on knowing which decisions were good after seeing the result. Echo is my attempt to recover some of that advantage without having that information in advance.

For each request, Echo decides how much computation to allocate, which models should participate, and how their work should be combined. Some prompts may only need a relatively small amount of inference, while others benefit from multiple models working on different parts of the problem.

One thing that surprised me while building it was how complementary the models are. A model that is clearly weaker overall can still be extremely useful on particular problems or as part of a combination.

On my first evaluation mix, Echo consistently performed better than the best individual model in its pool. It also reached roughly the same aggregate result as Fable, which I used as one of the stronger comparison systems, at around one third of the inference cost.

There are still some cases where Echo makes the wrong allocation or combination decision. I’m currently spending a lot of time understanding those failures, as well as testing whether the same approach holds up on coding and agentic tasks where measuring the quality of each decision becomes much harder.

I built a chat interface (echo.tracerml.ai) and an OpenAI-compatible API (https://echo.tracerml.ai/docs/api) so the system can be tested outside the evaluation setup.

Here is a short/high level video on how it works: https://www.youtube.com/watch?v=lJFJSvOdXhg

I wrote up the evaluation methodology, individual model results, costs and current limitations here: https://echo.tracerml.ai/eval

I would love for you to try it! Especially if you hit any weird failure cases or places where the allocation looks unintuitive.

dluan an hour ago | parent | next [-]

So this is the dogpile.com of the askjeeves, alta vista, and lycos approach? Time is a flat circle?

glasss an hour ago | parent | next [-]

Good ideas are usually still good across time and tools

alizaki an hour ago | parent | prev | next [-]

Indeed. What a deep cut

ignoramous 40 minutes ago | parent | prev | next [-]

Mixture of Models, perhaps? tbf to OP, the setup they're proposing has also been recently evangelized by other "ai gateway" products (like OpenRouter, JusCode, Fireworks etc), so there's likely something useful here.

fmajid 15 minutes ago | parent [-]

Ensemble Methods:

https://en.wikipedia.org/wiki/Ensemble_learning

cdelsolar an hour ago | parent | prev [-]

timecube?

kamranjon 3 hours ago | parent | prev | next [-]

No benchmarks, no info on which models are used, ai generated video, just a signup page with nothing else.

Anyhow, this kinda reminds me of that quote about architecture: "We replaced our monolith with micro services so that every outage could be more like a murder mystery."

adam_rida 2 hours ago | parent | next [-]

The evaluator is public here: https://echo.tracerml.ai/eval/

It currently exposes 907 stored rows across seven benchmark families, with prompts, outputs, grades, and cost records. More benchmarks are coming soon.

Echo does not disclose its per-request routing decision because that policy is the product. We can, however, publish some of the eligible open-weight model pool, version dates, aggregate allocation mix, and evaluation settings without exposing the request-level recipe.

New video is also being made.

guessmyname 3 hours ago | parent | prev | next [-]

> No benchmarks, no info on which models are used, […]

The benchmarks are here → https://echo.tracerml.ai/eval/

They are not good benchmarks but at least they exist.

seizethecheese 2 hours ago | parent [-]

I've been working on a similar project and I found that it's easy to replicate Fable results if you use saturated benchmarks.

In my project, I wasted a huge amount of time trying to improve GPQA Diamond results above ~93% range. I realized my mistake when Fable dropped and made no improvement on this benchmark vs. Opus.

codekansas 2 hours ago | parent | prev | next [-]

It's basically trying to replicate OpenRouter, which works pretty well and has a lot of nice features to abstract away any single provider, such as failover, metering, autoswitching, etc. It's actually a really smart infrastructure abstraction.

I just wish this were solving an actual problem rather than being a fairly transparent attempt to say something approximating, "Hey VCs, OpenRouter just became a unicorn but I can basically vibe code it"

Calling it "Fable-level" feels intellectually lazy / dishonest, but then again, what do you expect when there's so much money on the table.

vunderba 31 minutes ago | parent | next [-]

It feels a bit more like Fugu to me, which acts as a multi-LLM orchestrator (though I think Fugu combines open- and closed-weight models), but without being able to see the “secret sauce” behind how any of them decides the number of "plies" each model in the swarm gets, they all feel rather difficult to compare beyond the big public benchmarks...

https://github.com/SakanaAI/fugu

seizethecheese an hour ago | parent | prev [-]

OpenRouter's model router for coding isn't really sophisticated. This is very different.

dimitrios1 an hour ago | parent | prev | next [-]

Unrelated - but reminds me of my favorite quote by tenderlove:

"microservices turn function calls into distributed computing problems"

WD-42 an hour ago | parent [-]

grug wonder why big brain take hardest problem, factoring system correctly, and introduce network call too

seem very confusing to grug

j45 2 hours ago | parent | prev [-]

It's easy enough to copy and paste in a prompt, no?

Eval tests while giving general indicators might not be similar for each use case.

meander_water an hour ago | parent | prev | next [-]

Seems similar to Openrouter Fusion - https://openrouter.ai/docs/guides/routing/routers/fusion-rou...

seizethecheese 12 minutes ago | parent [-]

Fusion is a totally different approach, though similar in the sense that it leverages different models.

Fusion generates many replies then synthesizes. This adds a ton of latency and cost, so it's going to be better only for cases where you're willing to wait a lot and pay a lot more.

Routers (like this project) are a different thing, they can theoretically improve performance and cost at the same time without increasing latency much. I'm a bit skeptical though, since knowing which LLM is going to be better on a cost adjusted basis is hard (see https://artificialanalysis.ai/models/capabilities/coding?cos..., where the cost per task vs. performance is not what you expect, for example comparing Qwen 3.7 Max to GPT Sol.

A project I'm working on is aimed at improving performance without added latency but from a different angle. Instead of waiting for all replies for synthesis (like OpenRouter Fusion), it streams the "best" reply immediately (using a router to pick the best model) then synthesizes with emoji reactions and optional replies from the background models. It's free to use here with no login: http://pellmell.ai

slashdave an hour ago | parent | prev | next [-]

Replace "Show HN:" with "Advertisement:" ?

jmspring 29 minutes ago | parent | prev | next [-]

So the word security or any topic related to it is mentioned and it flips to an older gen model? Fable is nearly useless now it you do anything around auth.

dijit 11 minutes ago | parent [-]

I can get it to write win32 unsafe rust code.

I can't get it to review win32 unsafe rust code.

Make it make sense.

tj800x 3 hours ago | parent | prev | next [-]

No single signin. Privacy policy allows training. No try it first without credit card. It's a good idea, but this looks premature.

adam_rida 2 hours ago | parent | next [-]

You are right that the privacy wording was too broad. We are fixing it now so it states explicitly that Echo does not use customer prompts, files, chats, or outputs to train or fine-tune models. We are updating the matching Terms language at the same time.

Echo also starts users with free credit and does not require a credit card to try it. The current signup flow did not make that clear enough, so we are fixing that presentation too.

Thanks for calling both out.

seizethecheese an hour ago | parent | prev | next [-]

If you want to try a similar idea that you can chat with immediately (free tier uses open weight models), I'm working on this: http://pellmell.ai

cynicalsecurity 2 hours ago | parent | prev [-]

I assume trying without a credit card will bankrupt him immediately.

hmokiguess an hour ago | parent | prev | next [-]

"Backed by YCombinator"

https://www.ycombinator.com/companies?query=tracerml

I don't see it?

purplecats 8 minutes ago | parent | prev | next [-]

but u wouldnt get caching savings

3 hours ago | parent | prev | next [-]
[deleted]
adam_rida 2 hours ago | parent [-]

Thanks for checking the individual rows. HumanEval+ is one small code slice, not the whole basis for the launch claim. The public evaluator currently contains 907 rows across seven benchmark families, and matched SWE-bench Verified and BigCodeBench runs are the next code evidence being added.

You also found a real UI bug: the inspector should show both stored answers and currently does not in some rows. We are fixing that.

On the row you reran: the page records a frozen matched run. It does not claim that Fable is incapable of solving that prompt on another run. We are adding repeated matched trials and making run count and variance explicit. Your rerun is exactly the kind of external check the row-level page is intended to make possible.

The broader result remains: Echo is competitive with Fable across the evaluated task mix at materially lower measured inference cost. We are filling in the harder agentic-code evidence now rather than asking anyone to infer it from HumanEval+.

Alifatisk 2 hours ago | parent | prev | next [-]

This reminds me on OpenRouters report that combining multiple different models gave comparable performance to Fable 5. I think this approach has lots of potential. Maybe OpenAi was ahead of its time with GPT-5 (it being a router to different models rather than just being one new model)

seizethecheese 2 hours ago | parent [-]

You might be interested in a project that I'm working on, which is kind of like OpenRouter Fusion, but instead of waiting for all models to synthesize, we stream the best model immediately and background the rest. The background models then reconcile with an emoji reaction and optional reply. It gets similar results to Fusion and is a lot faster! There's a free version that leverages open weight models here: http://pellmell.ai.

NetOpWibby 34 minutes ago | parent | next [-]

I like that I was able to test without an account and my prompt (What's the feasibility of a NetNavi IRL, along with a PErsonal Terminal? Create a document that outlines how to make this happen.) makes me think Pellmell is gonna be a research tool I'll continue to use.

hmokiguess an hour ago | parent | prev [-]

This is really cool, super fun!

jmaw 3 hours ago | parent | prev | next [-]

I think approaches like this have potential. Only time will tell. This reminds me of the mixture of experts taken by deepseek r2 (I think it was r2, at least), but less specific models I guess.

I have often wondered how tools like GHCP choose the best model for the job when set to "auto".

yonatan8070 2 hours ago | parent | prev | next [-]

I'm not an expert on this, but this sounds a lot like a larger-scale MoE (Mixture of Experts) type of architecture.

As I understand it, in an MoE model, you essentially have hundreds of smaller sub-models ("experts") that are good at different tasks, and for every generated token, a single "master" model chooses which ones are most relevant to participate, and you only activate them.

janalsncm 2 hours ago | parent [-]

In MoE systems the routing decision is made per-token, not per prompt or task. It’s one of ML’s many confusing naming conventions.

Even more confusingly, there are older pre-LLM MoE systems which ensemble and pool the predictions from multiple sub-components. For example in a random forest you could take the majority vote of the decision trees or the average of their numerical predictions.

After that, we developed neural net architectures for predicting a single thing like whether the user will click on your ad. An MMoE is in the same family.

And so now we are at massive MoE networks for LLMs which have similarities with MMoE in that the “decision” is about the very next token to predict.

lukan an hour ago | parent [-]

"In MoE systems the routing decision is made per-token, not per prompt or task."

Have there been experiments with doing it per task? Like, "oh this is python project, use this model" "oh this is about writing fantasy, use this"?

janalsncm 8 minutes ago | parent [-]

It’s a good idea. The results probably depend a lot on how close your task is to the benchmarks though.

I think OpenAI already has (had?) a feature like this called “auto” mode for thinking.

janalsncm 2 hours ago | parent | prev | next [-]

Intuitively, your savings depend heavily on how hard the tasks are in the first place. If you have a base rate where 99% of your tasks can be routed to a cheap model, yeah, you can save a ton by not using Fable for that.

So “1/3 the cost” really depends.

indiantinker an hour ago | parent | prev | next [-]

I have been using this : https://magnitude.dev/ for a while now. Is it something similar you are doing? I would love to have something that would connect to my codex, Claude, and opencode subscription rather than having to make a new subscription.

maxdo 2 hours ago | parent | prev | next [-]

such a scam, there is only one fable-like model, that somewhat behind, it cost half, not 3x. so from here you can stop reading.

ninjahawk1 2 hours ago | parent | prev | next [-]

I’m very confused on what this is, my initial thought was “oh nice, open source router.”

I go to the website…and it’s a sign up. I expected a repo. Otherwise how do I use it? As a SaaS? Yeah right.

Oh well I guess at least the benchmarks are good…I find the benchmarks and many are either not present or are not what the title claims.

My main question is how this has so many updoots from HN, probably the passerby not looking closer for sure.

I mean no offense and I really do wish you best on this, but it seems like what we used to call back in the day, vaporware.

jacobgold 2 hours ago | parent | prev | next [-]

> Fable-level results at 1/3 the cost using open-weight models

But we get ~$2500/mo worth of Fable credits for $200/mo on Anthropic pan? I'm still confused why people (who don't have to use API billing) are chasing open weight models based on cost.

recursivegirth an hour ago | parent | next [-]

Enterprise plans pay API costs, they're only subsidizing individual accounts and that's only because they have to compete with open-source models.

When they are successful at making those illegal/inaccessible, both Anthropic and ChatGPT are going to rip the band-aid off and inference will only be sold to those that can afford it.

The good ole American way.

drnick1 an hour ago | parent [-]

> When they are successful at making those illegal/inaccessible

This would be like trying to outlaw Linux or peer-to-peer file sharing. It's technically possible to write and pass a law, but it's basically impossible to enforce it.

switchbak an hour ago | parent [-]

Enough to make it a non-started at the organizations that pay their bills. Everyone else isn't big enough to matter.

trollbridge an hour ago | parent [-]

Going to be an interesting world where big enterprises have to spend 100X the cost for the same value of AI as startups and small businesses.

teruakohatu 2 hours ago | parent | prev | next [-]

Because that is a short term solution, it won’t be offered forever. Large organisations have to purchase credits at $/tokens. Eventually everyone else will too.

sscaryterry an hour ago | parent [-]

This is what OpenAI and Anthropic are trying to make everyone believe. Most accountants will flinch at this (they already are).

The $200 odd plans are already out of reach of many, many people.

The attrition of customers if they were to get rid of these subscriptions plans would be untenable.

recursivegirth an hour ago | parent [-]

I think you are looking at it incorrectly. No business is buying individual accounts, because if they do, they open themselves up to considerable risk.

The $200 plans are priced so that the power-users use them and then advocate about how great the product is. If you're buying a $200 plan, you're not doing it because of the price point but rather because of the amount of work it is doing for you.

trollbridge an hour ago | parent [-]

Lots of businesses are buying and using these plans. Basically every small business I interact with.

eikenberry an hour ago | parent | prev | next [-]

I think most people assume the subsidized plans will go away or get more limited eventually. They are basically a loss leader and a marketing cost that is very flexible and easy to change w/o directly impacting their primary customers.

combyn8tor an hour ago | parent | prev | next [-]

You may want to consider the incomes of developers outside the US, students, unemployed. $200/month is a lot to a lot of people.

gruez an hour ago | parent | next [-]

The point still stands. The chinese labs don't have super discounted plans, so if the price per task benchmarks[1] are correct, and we apply the discount, you'll actually be paying more by using cheaper chinese models and this technique.

https://artificialanalysis.ai/agents/coding-agents#artificia...

dbbk an hour ago | parent | prev [-]

They can still write code.

dberg 2 hours ago | parent | prev [-]

doesnt exist for enterprise plans

bbstats 2 hours ago | parent | prev | next [-]

M-o-MoE

bnjemian 2 hours ago | parent | prev | next [-]

I don’t find the recent spate of blog posts and systems delegating and combining LLMs to get better performance particularly interesting. Especially given that anyone who’s taken an ML 101 course has learned about ensemble methods.

While an LLM isn’t what you’d traditionally consider a weak learner, the theorems on learning systems clearly point to them being so in this context. The feigned surprise at combining them to yield better results seems disingenuous.

Even so, the work to predict which models are best suited for which task, how to delegate, and how to combine their outputs is interesting, especially if you’re placing a cost minimization objective on it. That said, this isn’t too far off from what many AI labs are already doing.

abernard1 2 hours ago | parent [-]

The entirety of "agents" and tool calls is a process of combining LLMs to get better results. Is it the same LLM in many cases? Yes. But it doesn't have to be.

It's the natural move that happened after people realized you couldn't throw away half a century of AI research.

Most of these focus on costs. But it is simply the case that the one-shot output did not scale for harder problems on workflows.

fneddy 3 hours ago | parent | prev | next [-]

That’s basically the same idea IBM advertises with Bob?

wizche 2 hours ago | parent | prev | next [-]

how does this differs from OpenRouter fusion?

cawingcrow 2 hours ago | parent [-]

how does this differs from Sakana Fugu?

codekansas 2 hours ago | parent | prev | next [-]

Fable-level, yea, but can it run gstack?

jambalaya8 2 hours ago | parent | prev | next [-]

Might want to rethink the name to avoid an Amazon issue.

j45 2 hours ago | parent | prev | next [-]

If you copy Perplexity, they let you have the first few rounds of chat for free to get you going before asking to sign up.

ototot 2 hours ago | parent | prev [-]

Is this yet another Sakana Fugu / OpenRouter Fusion?

kachnuv_ocasek 2 hours ago | parent [-]

Looks like it but with open-weights only.