AI Engineer World's Fair 2026
Stop Renting Intelligence: The Train-to-Deploy Loop for Specialized AI — Fireworks AI
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Stop Renting Intelligence: The Train-to-Deploy Loop for Specialized AI
Jetashree Ravi explains how Fireworks combines workload-specific inference, several levels of training control and checkpoint deployment to help teams specialize open models—and keep updating them with production feedback.
From a talk by Jetashree Ravi
At a glance
Ideas worth remembering
Quality tuning and serving optimization address different problems: the Genspark example changes data and evaluation for RFT, while FireAttention targets workload-specific execution.
Choose the training interface by the control required: delegate setup to the agent, configure a managed run or define custom loops and losses through the training API. The agent does not support RFT in this presentation.
Hot loading addresses deployment downtime when replacing weights; numerical fidelity addresses quality changes caused by differences between training and serving numerics.
The demonstrations retain inspectable decisions: approve the agent’s proposed plan, examine completed-job settings and loss, clone a run with changes and choose a serving configuration for deployment.
A cheaper model still has to do the job
The opening question is familiar to anyone paying for model APIs: how quickly is the bill growing? Jetashree Ravi, who leads part of Fireworks AI’s applied machine learning team, starts with teams considering a move from closed models to open models for cost or performance reasons. The difficult part is keeping the quality users already expect. A cheaper response is useful only if it still completes the task.
Ravi builds the talk around three premises: open models are already production-ready for many workloads, customization can close remaining task-specific quality gaps, and deployed models increasingly need repeated training rather than a single release. These are the premises behind Fireworks’ combined training and serving product. The intended unit of work becomes a continuing sequence of checkpoints: train a model, serve it, learn from use and train it again.
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Speed and quality are separate migration problems
Fireworks approaches this as a production infrastructure problem. Ravi reports serving about 30 trillion tokens, supporting more than 10,000 companies and processing about 200,000 requests per second. The token total has no clear reporting interval in the recording, so it is best read as a scale claim rather than a comparable throughput measure.
The customer examples distinguish what teams need to improve:
- Cursor: inference speed. Composer 2 was trained and hosted on Fireworks. Ravi attributes a reported 13× inference speedup to the FireAttention engine.
- Vercel: serving latency. Fireworks helped fine-tune and host its model, with a reported 40× latency improvement.
- Genspark: task quality. Quality was a bottleneck when moving from closed to open models for a product that lets users design systems through prompts. Fireworks cleaned the dataset, helped define evaluator functions and ran reinforcement fine-tuning, reporting a 12% quality improvement.
These are Ravi’s reported customer outcomes, with no comparison baselines, workload specifications or quality-scoring protocol supplied. In particular, the 12% figure does not establish whether the change is relative or measured in percentage points. The useful technical distinction is the work behind each result: serving optimization addresses execution speed, while Genspark’s intervention changes the training data and the evaluator used to guide learning.
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Optimize the inference stack for the traffic it will receive
FireAttention is Fireworks’ inference engine. Ravi explains its role through the path between a model and the GPUs executing it: CUDA kernels implement the GPU work, and Fireworks builds its own kernels as part of the engine. That gives the team a place to optimize execution for a customer’s workload, alongside changes elsewhere in the serving stack.
The input to this optimization is more concrete than “make the model fast.” A customer supplies input-token lengths, output-token lengths, a prompt-cache hit rate and a latency target—Ravi’s shorthand is X, Y and Z. Those properties describe the traffic the system must handle. Fireworks then tunes the stack, including kernels, toward the requested latency and a lower serving price. The optimization is tied to that traffic profile; the talk does not present a universal configuration that delivers the same gain for every workload.
The engine also uses speculative decoding, disaggregation and quantization. The concrete extension described here is training a custom draft model for speculative decoding: customers upload a dataset, much as they would for fine-tuning, and train the draft model on the platform. Ravi links a well-trained draft model to faster main-model inference, better throughput and meeting latency requirements. The recording does not develop the decoding algorithm or quantify the draft model’s contribution separately.
There is a practical ordering to these decisions. Customers generally reach this stage once they are satisfied with model quality. If an open model still gives inadequate answers, faster execution leaves the main migration problem unresolved. That moves the discussion from serving optimization to training.
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Three interfaces divide the work differently
Fireworks offers three ways to train, distinguished by how much of the training process the user wants to specify. Choosing among them means deciding whether to delegate configuration, supply it directly or write the learning procedure.
- Training agent: delegate setup. Through the UI, a user points the agent to an uploaded dataset and describes the goal. The agent can help select a model, clean data and choose hyperparameters. Ravi positions it for product managers and builders who are newer to training.
- Managed training: supply the configuration. Through an API or UI, the user chooses a model, uploads data and sets hyperparameters, then starts a job. The service handles execution. Ravi describes this as the option most customers use.
- Training API: define the learning procedure. ML engineers can write their own training loop and loss functions when the managed service does not provide the control their task requires.
Managed training also makes the running job inspectable. Its dashboard shows progress across epochs and the training loss, so users can examine how learning proceeds after launch. Teams already using Weights & Biases can supply an API key and export some observability metrics there.
The training ecosystem includes supervised fine-tuning, reinforcement fine-tuning and DPO, but the interfaces do not all support the same methods. The important exception is the training agent: it does not support RFT in this presentation. Its automated dataset cleanup and hyperparameter assistance therefore do not extend to RFT. For that work, Ravi describes direct help with evaluator design, dataset cleaning and hyperparameter selection—the same pieces involved in the Genspark example.
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Keep the checkpoint moving from training into production
The continuing train-to-deploy process begins with a trained checkpoint that can be deployed from the same platform. Once it is serving traffic, monitoring exposes token counts, cache hit rates and the behavior of a trained speculator. Those metrics and user feedback can inform another training run, continuing from the existing checkpoint to a new one. Retraining remains a choice; the description does not imply that every observed metric automatically updates the weights.
Compute availability supports both sides of this process. Fireworks partners with cloud and neo-cloud providers to obtain GPUs for training and hosting at scale. Two other capabilities address the handoff between checkpoints: hot loading changes the weights in a live deployment, while numerical fidelity aims to preserve the behavior obtained during training.
Hot loading was initially implemented for Cursor and then offered more broadly. When a new checkpoint is ready, the user can swap the deployed weights for the new weights without downtime, as Ravi describes it. This makes an existing deployment the destination for successive training results. The talk explains the user-visible operation, without detailing the internal weight-loading or request-handling mechanism.
Numerical fidelity addresses a different failure: a model trained on platform A can lose quality when served on platform B because the numerical behavior differs. A deployment can therefore succeed operationally while failing to preserve the trained model’s quality. Fireworks’ stated promise is to align training and inference numerics on its platform so this handoff introduces no numerical differences. No numerical tolerance or validation procedure is given, so the promise should not be read as a demonstrated guarantee across arbitrary external stacks.
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The training agent proposes a plan before running it
The first demonstration starts with two inputs: the location or name of the training dataset inside Fireworks, and a separate evaluation dataset. The user asks the agent to fine-tune a model and choose both the base model and hyperparameters. This delegates the setup decisions while still giving the run distinct data for training and evaluation.
What can the user inspect before the job starts? The agent returns an SFT plan, explains its base-model selection and describes the proposed hyperparameters and high-level training process. The user approves that proposal before execution. The consequential transition is from a requested goal to a concrete training plan, followed by an explicit decision to run it.
After approval, the agent reports progress through the steps. At completion, it summarizes the configuration, base model and hyperparameters, then returns evaluation metrics such as accuracy and F1 score, along with recommended next steps. These are the described outputs of the demonstration; the recording supplies no metric values from which to judge this particular run’s quality gain.
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Managed training exposes the configuration and the completed run
The managed-training demonstration makes the user responsible for the choices the agent previously proposed. After uploading a dataset and choosing a model, the user selects an evaluation dataset in the evaluator settings. Optional settings allow finer control over hyperparameters. Clicking Create starts the training job.
What remains available to inspect after training? Opening the completed job reveals the dataset, hyperparameters and loss during training. A run can also be cloned with different settings. That connects a recorded configuration to the next experiment: retain the earlier setup, change the desired settings and launch another run rather than reconstructing it from memory.
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Deployment still requires a serving configuration
How does the trained model become a serving deployment? In the Deployment section, the user selects the newly trained custom model, chooses deployment settings and clicks Deploy. Available templates include throughput, fast and minimal. Ravi describes them as configurations optimized for generic workloads using throughput, latency, time to first token and related metrics. The choice matters because training produces the model, while deployment settings determine how it is served.
The ending leaves the most customizable route open. There is no complete training-API demonstration because its setup varies by customer; Ravi points engineers toward cookbooks for custom loops and loss functions. The demonstrated path is narrower and concrete: configure or delegate a training run, inspect its results, select the resulting custom model and deploy it with an appropriate serving configuration. The earlier hot-loading capability then provides a way to bring subsequent checkpoints into the live deployment.
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Resources
Related talks
- Beating RL With Reflection: GEPA and Optimize Anything
Explores a complementary route to specialization: using execution traces and evaluator feedback to improve prompts, agent programs and skills, with an ending that considers combining those changes with weight training.
Read the complete timestamped transcript
- 0:12
Hi, everyone. Uh, before we get started, I actually have a quick question for all of you. How many of you actually today used a closed source model like ChatGPT or Anthropic? Okay. How many of you feel like it's getting really expensive really quickly?
- 0:31
Okay. That's, that's a good percentage of you all. And, uh, just like all of you might be thinking of switching from closed source model to open source models for cost reasons, performance reasons, there are, uh, other customers and users that are going through the same journey. And today, I'm going to talk about where these open source models shine and how to make the performance or quality of these open source models match the closed source models
- 1:01
itself. And before I get into that, quick introduction of myself. Uh, I work at Fireworks. I lead part of the applied machine learning team. My name is Jetashree, but feel free to call me Jat if that's easier. Um, let's talk about the whole train-to-deploy loop that, that the open source models are taking today when users are switching from closed source to open source models. But even before we get into that, let's talk about some fundamental truths that are true today
- 1:31
in the AI ecosystem. So the th-three fundamental truths that are true, uh, are one, open source models, for the most part, are production ready. If any of you have used GLM 5 point-- 5.2, you know that that is true, especially for the coding use cases. Two, if open source models don't, like, beat or match the quality of closed source models, the differentiating factor, uh, comes from how you customize, train, and improve these open source models to
- 2:00
match the performance and quality of closed source models. And three, the AI stack itself for most of our customers and users is shifting from, "Let's just sell a model once it-- once and that's done" to a more continuous loop that is improving from training to inferencing, uh, the same open source model itself. So that's where Fireworks kind of comes in. It makes the whole process of you having to go through the continuous
- 2:30
journey of training these open source models, as well as hosting these open source models at scale much more easier and also much more cost effective as well. And I'll get into how we actually do the training itself and different flavors of training that we offer towards the end of the presentation. But I did also wanna quickly talk about inference before we go to the training portion of it, which has become really popular among our customers and user base. And before we also talk about inference and training, I just wanted to give you a quick overview
- 3:00
of how, uh, inference looks like, especially at scales, and what are the kind of production impact that we have seen among some of our customers and user base itself. So today at-- in production at scale, uh, we serve about thirty trillion tokens, and it's increasing. Um, this number was actually pre-GLM 5.2 release. I'm sure this has pretty much kind of increased by about at least five trillion tokens a day now with the GLM 5.2 release.
- 3:30
We support more than ten thousand companies globally and process about two hundred K requests a particular second itself. And the kind of production impact that we are seeing within our customer and user base is very significant. So Cursor, uh, if-- for those of you who already use Cursor and Cursor models, uh, the Composer 2 model for Cursor was trained and also hosted on our platform today. And, um, it is able to achieve
- 4:00
thirteen X faster inference because of the FireAttention engine that we have. And I'll speak a little bit about that in the next slide as well. Uh, Vercel is also another big customers, uh, of ours. We help them actually fine-tune and also host the model on our platform, and they see a forty X latency improvement. And another u-big use case study is actually Genspark. Um, Genspark lovables are in very similar field where they actually let you design systems with just
- 4:30
prompts itself. And, uh, quality is a big bottleneck or was a big bottleneck for them when they were trying to switch from closed source to open source models, and we helped them fine-tune. We did, uh, RFT for them. We helped them clean the dataset, define evaluator functions, and at the end of the RFT training job itself, we saw that there was twelve percent quality improvement for the Genspark use case. Um, also, we are a, a trusted platform among a-all our other
- 5:00
customers and user base as well, and we have raised, uh, around three twenty-seven million CDC, uh, a while ago, and we are about two hundred people working at Fireworks. That brings me to the next portion of it. I know in the previous slide I did mention that we made latency faster for a couple of our customers, such as Vercel. And how we do it is quite simple a-at a, at a higher level. Um, at Fireworks, we have our own inference engine called FireAttention.
- 5:30
So you have a model, you have GPUs, and the way the model sits on top of the GPUs is through a translation layer called CUDA kernels. And as part of FireAttention, we build our own CUDA kernel. So when a customer comes to us, uh, uh, with a workload and a performance target in mind, then we can optimize this particular inference engine and the whole AI stack, including that CUDA kernel for that specific use case. So most of the time, customer like Vercel in the previous slide, come to us and tell us, uh, they have X
- 5:59
input tokens, Y output tokens, uh, they have Z prompt to-- uh, prompt cache hit rate, and they wanna meet so and so latency targets. And we help them optimize this whole inference stack, including that CUDA kernel, so that we can serve this model, uh, at a cheaper price, but also at a-- uh, that can meet their performance target and for their specific workload itself. Uh, as part of FireAttention and inference optimization, we do also implement the very well-known
- 6:29
techniques in the AI field, which is things like speculative decoding, disaggregation, quantization. In terms of speculative decoding itself, we also allow customers to train their draft models on our platform. Uh, so they can even upload the dataset, very similar to how they do for fine-tuning, for, uh, training a draft model, uh, which helps them, uh, make the model, the main model, uh, perform much faster, uh, meet latency requirements, also gives you
- 6:59
better throughput if the draft model is trained, uh, very well. And, um, so once people actually-- people actually get to this stage mainly once they're happy with model quality. But when customers are switching from closed source to open source models, the biggest bottleneck or the gap is quality. And the way we, we try to solve for it is through our training product. And our training product itself comes in three different flavors for different
- 7:29
segments, uh, within our customer and user base, one being the training agent. This is very popular among our product managers and builders that get in-- that got into this AI inferencing and training field very recently. So the agent can be accessed through our UI, and, uh, you can-- you, you just need to link it the dataset that you have uploaded, uh, on the Fireworks platform, as well as description on what you're trying to do as part of
- 7:59
this training run itself. Uh, it will even let you choose the model. It will clean the dataset for you. It will also help you do the hyperparameter, uh, fine-tuning itself, 'cause it's not always easy to get the right, uh, hyperparameters itself, um, when you are doing training for your specific workload. The next flavor, al-also one of our most popular flavors among our customer and user base, is our managed training, and this is what most of our customers use today.
- 8:29
They can use our managed training platform, one, through API and second through the UI itself. It is as simple as you inputting the hyperparameters that you think will be good for your model, choosing a model, uploading the dataset itself, and then clicking a button. That's how simple we make it on, uh, Fireworks for the managed training itself. And, uh, I know one challenge a lot of people have is observability once the training run itself kicks in. So we
- 8:59
also have a good UI dashboard that shows you how the training, uh, is happening, how well your model is, uh, learning at each epoch, what does the loss function look like. Additionally, you can also plug in, uh, your Weights & Biases API key into the managed training service itself, uh, and export some of the observability metrics to platforms like Weights & Biases if you're already using that. And the third and the kind of the most advanced flavor of training that we offer is the
- 9:29
training API itself. And the training API is very popular among some, uh, of the ML engineers within, uh, different organizations or within our customer base. And in this, in this particular-- this particular offering of the product lets, uh, ML engineers define their own training loop and loss functions. And this becomes important when you want to customize your training job according to your needs that is-- that goes well, uh,
- 9:59
above, beyond the managed training service that we offer itself. And these, these different, uh, flavors or the products within the training ecosystem that we offered are offered for, uh, supervised fine-tuning, reinforcement fine-tuning, and even DPO as well. Um, nowadays, I think RFT has become extremely, extremely popular. And if you ever need help in helping define a good evaluator function, then we have worked with customers like
- 10:29
Genspark, that I was talking to you about in the previous slide, to help them define an evaluator function, clean the dataset, um, and also choose the right hyperparameters, especially for RFT. Unfortunately, the training agent itself does not support RFT, so it does not, uh, help you clean the dataset or even do the hyperparameter tweaking. But we are more than happy to help you do it if you have a big use case in mind. So now that we know all about the different, uh, training
- 10:59
offerings that we have, I also wanted to show you a quick demo of each of these, the training agent, managed training, and the training API itself. Uh, but before we get into that, I just wanted to close off by saying how the data flywheel looks like today on our platform. I know in the first slide, I was talking to you about the realities of AI today, where most people prefer doing a continuous loop, where they train, host, train, host as they get new and new data and feedback from their users. And that is
- 11:29
what we are trying to make more seamless on our platform, and that's also why we have different training products, different offerings, as well as making it easier, uh, for you to host and make it also cheaper and faster for you to host those models at scale itself. And the way this flywheel works is kind of very simple. Once these, uh, models are trained, I will show you, uh, a demo in the next slide where the models get trained. It's, it's-- you just are one click away from deploying these models into
- 11:59
production. And once you've deployed, you can, uh, monitor. We have, uh- Monitoring metrics for the number of tokens, cache hit rate, how your speculator is working if you've trained a speculator. Uh, we help you collect gathered, uh, feedback from all the, all the metrics that you have collected, and if you choose to also retrain on the same platform from the end-- from the checkpoint that you were using to a new checkpoint itself. So some of... some capabilities on the platform
- 12:29
that makes these data flywheel possible is, one, definitely having a host of, uh, GPUs. We do have-- We do partner with different cloud and neo-cloud providers, which makes it easier for us to provide compute and also host these models at scale. Another thing i- we offer is hot loading, and this has become really popular, especially when we were training models for Cursor, and this was actually a feature we implemented specifically for Cursor, and then we thought would be useful for general public while they were training
- 12:58
models as well. Uh, what hot loading essentially means is when you have a new checkpoint, uh, you, you can directly go to live deployment without any downtime itself. So if you have a deployment and you've gone through this continuous loop and trained a new checkpoint, then you can just click a button and swap out the weights itself that you were using, uh, uh, previously with the new endpoints. Another thing that makes it, uh, easier to train on our platform is the numerical fidelity. So a lot
- 13:28
of the time customers use platform A for training and host on platform B. But what happens when you do that is you'll have issues in quality of the model, and the reason you have those issues is numerics is not always compatible when you train on a different platform and host on a different platform. So that's why we offer training and inferencing on the same platform and ensure that, uh, you won't find any numerical differences after you finish training and once you decide to host this particular model on the platform
- 13:58
itself. And, um, one other thing that, that makes it more seamless is because training and inference is on the same platform, you're just one click away from, uh, deploying this model at production scale. Now that we've learned all about, uh, the inference and training, I just wanted to show you a quick demo of different training products and how they work on our platform. The first portion of the demo is showing you how you can use the training agent itself. Over here, you
- 14:28
can, uh, input where your training dataset lives within the Fireworks, what it's called. Uh, you can also, uh, give it the eval dataset itself. Uh, I know people have the train and eval or a test dataset separately, so you give the mo-- you give the agent both the datasets, and then you ask it, uh, to fine-tune and even select the hyperparameters and the model for you. The, the agent then goes on and tells you the step that it will,
- 14:59
it will take to accomplish the task that you have given it. So it, it details the SFT plan. It tells you why it selected the base model. In this case, it selected Qwen3-8B. And it'll also give you some information on the hyperparameters and what the whole training process can look like at a high level. And once you're done, uh, once you are, uh, you feel okay about the output that the agent has given, you can approve whatever the agent has, uh, the a- the agent has outlined. And
- 15:29
once you approve it, it will actually go through different steps and keep you posted on if it finishes step two, what does, uh, it look like? If it successfully finishes step three, what does that look like now? And at the end of the whole training run, it will also give you a summary of, uh, the config, the base model, um, and, uh, different hyperparameters and how that impacts it as well.
- 15:59
And once it's-- once the whole model training is done, it actually gives you metrics such as accuracy and F1 score, uh, and it also summarizes, kind of re-summarizes and gives you an overview of everything that, uh, that it did. And one cool feature is it also gives you recommended next step as part of, uh, the training run itself. Now, the next portion of, uh, this demo actually talks about how we can use our, uh, managed training platform. I did mention that you just
- 16:29
have to select the model dataset and the hyperparameters, and then you're just a button click away from actually training a model. Say you've uploaded, uh, the dataset, chosen a model, uh, all you'll have to do is then, uh, go to the, go to the, uh, evaluator, uh, settings, choose the evaluator dataset, and also you get to choose the hyperparameter as part of optional settings if you decide to have a more fine-grained hyperparameters for your, uh, training run itself.
- 17:00
And once you're happy with all the configurations, including the model and the dataset itself, you just need to create, uh, you just need to click on the button that says Create. Um, and as soon as you click on the button that says Create, a, a training job then ki-kicks out, and you can see that, uh, the UI looks, uh, similar to this when a training job actually gets completed.
- 17:26
And if you click on that particular training job itself, it'll give you information on the dataset it used, the hyperparameters it used, what the model loss itself looks like when the model was training, um, and then you can even clone these training runs and reproduce it with different settings and configurations itself.
- 17:47
And once you're happy with the fine-tuned model, you can go to the Deployment section, choose the custom model that just got, uh, trained on our platform, and then click on Deploy once you're happy with the deployment configurations, or you can choose a set of deployment configurations that we have, such as throughput, fast, minimal, uh, and this is, uh, kind of a template that, that works well for generic workloads that we have optimized based on throughput, latency,
- 18:18
uh, time to first token, and other such metrics.
- 18:23
And, uh, I unfortunately don't have an entire demo for our training API because the setup itself differs from customer to customer. But we do have a lot of cookbooks on our websites that you can see and follow, especially if you're interested in customizing your own training loops and loss functions itself. Uh, and that's all I have for you for today. I just wanted to give you a brief overview of how the whole training to inferencing loop looks like. Thank you very much, and if you
- 18:53
have any questions, I'm happy to take them in the next minute or so that we have.