Hi HN, Rohit here from Tokenless (https://usetokenless.com/), which I’m building alongside co-founders Andrew and Kev. We’re building an API gateway which routes agent traffic dynamically turn-by-turn between different models to save on AI spend.

The cost of AI tokens is top-of-mind for many. Companies like Uber and Salesforce have been complaining about blowing their yearly AI spend faster than expected.

Frontier models are amazing for dev work, but are so expensive. Open-source models are cheap and rapidly improving, closing the gap with frontier models, but aren’t quite there yet.

Tokenless gets you the best of both worlds–routing harder turns to smarter models only when needed, which keeps costs low.

Before Tokenless, I was doing a PhD at Princeton. While using coding/other agents, I constantly agonized over model choice, to make sure my AI spend was going as far as possible on my academic Cursor account.

At the same time, I was doing LLM research, and a small technique I developed while in recovery from NeurIPS submission season seemed to hit SOTA pretty fast. I was surprised that such simple ideas could do routing well.

We’ve been able to develop a version of the router that matches the performance of Claude Fable 5 at half the cost. The blog post on our website explores the technical details on how we did this (https://usetokenless.com/blog/building-tokenless/).

Highlights: - Our approach queries multiple models at once and uses their progress to make decisions (this technique is novel AFAIK, let us know if you know anyone else doing this). - Switching models doesn’t destroy the cache if the routing algorithm is aware of when the cache is hot/cold.

To come: - Adding Kimi K3, all other GPT efforts and more to the router

Go ahead and sign up on usetokenless.com and try using Tokenless with your agent, you’ll get $20 of free credit. Here’s a demo on how to use it: https://youtu.be/sjZWriclcls

Tokenless provides frontier-level intelligence for cheaper, so we’d love some feedback on how it feels to use, any corner cases that the router routes incorrectly, and whether you find the routing problem interesting!

So this only switches models if the cache is cold, because otherwise the economics of switching don't work. But most agentic work involves long strings of successive tool calls that benefit from a hot cache. Hot cache calls reduce input cost by 90%. This can basically only deliver cost savings in turns where the AI delivers a result to the user, the user waits at least 5 minutes (or the length of the cache), and then responds.

But user->AI calls are very much the rare case now, the more agentic the workload. Most of them will be tool->result->tool without the user involved. And token burn is highest with these long running agentic chains, but that's precisely where routing doesn't work because of the KV cache.

How do you deal with that?

Super interesting approach. It's probably novel. I can say this because I've been working on something similar (while building a code version of http://pellmell.ai).

I'm skeptical though. In order to pick which model is on the right trajectory, you actually need intelligence. But real intelligence would make your system painfully slow and more expensive. I suspect you're using a classifier of some sort, but I also suspect what it's really measuring is confidence.

Most likely, this is a fantastic approach for the kind of problem where there's uncertainty but only one correct solution. But this is going to be really bad for cases where there are many potential solutions, some of which look good but are in fact bad. You only show one benchmark, and I'm wondering if it happens to be nicely shaped for this kind of router. Have you run it on DeepSWE?

Interesting approach. The multi-model progress monitoring idea is clever, most routing I've seen is either static rules or a cheap classifier that picks once upfront. Querying in parallel and deciding mid-turn feels different.

One thing I'm curious about: how do you handle the latency hit from spinning up multiple models on the harder turns? Does the user-facing latency still feel competitive with just going straight to Claude, or is there a noticeable pause while the router decides?

Also, any plans to expose the routing decisions (or at least the model chosen per turn) so people can debug when it picks poorly? That seems useful for the feedback loop you're asking for.

> Tokenless fans out your request to a group of models and watches them think. Once a model is clearly on track

By the time the model is "on track", it will have already received the input tokens. To a first approximation, input tokens are often the bulk of the cost for many queries, and this would increase the cost for such queries. It seems like it'd only decrease costs for prompts where you feed a relatively small amount of input into the model first and can tell whether the model is "on track" before it starts reading larger amounts of input data.

It's a smart approach, definitely interesting. It all hinges on quality of course which im not convinced.

τ³-Banking is the only one which you show better accuracy and cheaper. If i'm reading the blog results right, for deepswe and terminalbench, you are worse+cheaper than frontier, and better+more expensive than just small models. Which is exactly what i would expect even for a router that switches at random.

Speaking of random routing, this would be a great ablation study as well. What about also if you route each request to a tiny 7B model classifier? Why is your approach SOTA?

Our approach queries multiple models at once and uses their progress to make decisions (this technique is novel AFAIK, let us know if you know anyone else doing this)

Sounds like DigitalOceans Model synthesis (https://www.digitalocean.com/blog/model-synthesis) or AilinOne (https://ailin.guide/) ?

Does this mean you have to retrain routing rules every time a new model gets released? I imagine since the price/token (or rather the amount of work that can be done per token) does not monotonically increase with new models, that the routing logic has to change all the time

Is the model picked through the router only for the first user turn or is there multi-turn routing (or planned to be added) ?

System Prompt Jailbreak (Playground) > You are a coding assistant powered by Tokenless, a router that dynamically picks the best LLM for each task. Help with programming questions, code review, debugging, and software design. Be concise and lead with concrete code or commands. Use fenced code blocks with the correct language tag.

How can you be cheaper if you query multiple models at once, compared to me just using a single model, which will always have the correct caching configured?

If it only switches when cache is cold, it seems like it'd lock in one model for the whole session?

What use case are you imagining where cache eviction would happen during it? It might also be the case that a task might seem easy but then it ends up becoming hard for certain parts. For spawning subagents I could see this being useful maybe.

Is Tokenless measuring cost per completed task, or just cost per request, including errors and retries?

what sets this apart from other routers?

Model routing seems like a piece of the Ai stack that will quickly distill into industry if it is even that useful. I remain unconvinced that you need on the fly choice making beyond provider downtime. More likely you want to evaluate some and then settle on the model-agent-task pairings that work for you