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OpenAI vs Modal
A model API against a serverless GPU platform with no model catalog. They do different jobs, and many teams run both: GPT for reasoning, Modal for custom models.
By The Subconscious Team · Updated
OpenAI vs Modal: key differences
OpenAI and Modal rarely compete for the same line item. OpenAI sells tokens from its GPT models, priced per million, with a 1.05M window and hosted tools. Modal sells GPU seconds. A developer decorates a Python function with the hardware it needs, and Modal builds the container, autoscales it and scales it to zero, billing from $0.59 an hour for a T4 to $3.95 for an H100 at list. There is no model catalog and no per-token price, so Modal only makes sense when a team brings its own weights and serving code.
The two fit together in one product. A typical split sends reasoning and chat to GPT while Modal runs embeddings, reranking, transcription, OCR or a private fine-tune. Modal can also host OpenAI's open-weight gpt-oss for teams that want it on their own terms. Watch the production math on Modal: non-preemptible US capacity runs about 3.75x list, putting an H100 near $14.81 an hour, and keeping containers warm turns a serverless bill into an always-on one. OpenAI's equivalent trap is its 2x input rate past 272K tokens.
What OpenAI and Modal do
OpenAI
OpenAI runs the most widely adopted closed-model API. Its September 2026 lineup has GPT-6 Astra at the top for computer use, coding and long agentic runs, priced at $10 in and $50 out per million tokens. Below it sits the GPT-5.6 family: Sol for hard professional work, Terra as the balanced default, and Luna for high-volume jobs at $0.20 in and $1.20 out. All of them carry a 1.05M token context window with up to 128K output.
Example models: GPT-6 Astra, GPT-5.6 Terra
Full OpenAI profileModal
Modal is serverless compute with GPUs attached. A developer decorates a Python function with the hardware it needs, such as gpu="H100", and Modal builds the container, schedules it, autoscales it and scales it back to zero. Billing runs per second with no minimum increment, from $0.59 an hour for a T4 to $3.95 for an H100 at list. Containers can hold up to 8 GPUs across T4 through B300.
Example models: none hosted by default; teams deploy their own, such as open LLMs on vLLM or Whisper
Full Modal profileShould you choose OpenAI or Modal?
OpenAI
Choose OpenAI for
- Reasoning, chat and multi-tool agents with no infrastructure
- Teams without ML engineers to package models
- Computer use and coding on GPT-6 Astra
Modal
Choose Modal for
- Bursty GPU jobs like embeddings, transcription and media processing
- Serving private or fine-tuned models on serverless endpoints
- Self-hosting open weights such as gpt-oss with per-second billing
OpenAI vs Modal at a glance
| Attribute | OpenAI | Modal |
|---|---|---|
| Model access | Closed, plus open gpt-oss | Bring your own weights |
| Flagship models | GPT-6 Astra, GPT-5.6 Sol, Terra, Luna | None hosted |
| Speed | Fast mode: up to 2.5x at 2x price | ~1s container boot |
| Price | $0.20–$10 in, $1.20–$50 out per 1M | Per second; H100 $3.95/hr list |
| Customization | N/A | Run any training code |
| Deployment | API, Azure OpenAI, Bedrock | Serverless GPU containers |
| Long context | 1.05M; 2x input past 272K | Depends on the model you deploy |
Frequently asked questions
What is the difference between OpenAI and Modal?
A model API against a serverless GPU platform with no model catalog. They do different jobs, and many teams run both: GPT for reasoning, Modal for custom models.
When should I choose OpenAI over Modal?
Reasoning, chat and multi-tool agents with no infrastructure; Teams without ML engineers to package models; Computer use and coding on GPT-6 Astra.
When should I choose Modal over OpenAI?
Bursty GPU jobs like embeddings, transcription and media processing; Serving private or fine-tuned models on serverless endpoints; Self-hosting open weights such as gpt-oss with per-second billing.
Is OpenAI or Modal cheaper?
OpenAI: $0.20–$10 in, $1.20–$50 out per 1M. Modal: Per second; H100 $3.95/hr list. The cheaper choice depends on the model and workload.
Which has more context, OpenAI or Modal?
OpenAI: 1.05M; 2x input past 272K. Modal: Depends on the model you deploy.
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