OpenAI

OpenAI

GPT-OSS 120B

#5 on Kyma

OpenAI's open-source 120B model, and a workhorse on Kyma — strong-tier quality at cheap-tier pricing, steady across high volume. Reach for it when you want dependable general intelligence and writing without flagship cost.

Modalities

Text → Text

Weights

Published

openai/gpt-oss-120b

Where it sits in the catalogue Kyma measures

Every number against every text model Kyma prices per token — a stated rule, not a chosen line-up.

Price · input#1/70

$0.0494

output $0.2406

median $0.977 · best $0.0494

Price · output#3/70

$0.2406

per 1M tokens generated

median $3.531 · best $0.2164

Availability · 30d#50/68

92.43%

700 observations since 2026-05-02

median 96.2% · best 100.0%

Throughput#42/68

34.2 tok/s

probe median, one fixed prompt

median 40.8 tok/s · best 308.3 tok/s

Response time#50/68

3.58 s

probe median, to a complete answer

median 2.50 s · best 0.52 s

Context

128K

max output 8,192

published by OpenAI, not measured here

Tick above each rail is this model, below it the other 69. Dashed rule is the field median, solid is its best. Better is left; the axis stops at the 90th percentile, so a few models sit past its right edge.

Usage

How much this model is actually called here.

Rank

#5

of 113 active models

Tokens served

125.6M

all-time

Platform share

3.9%

of all tokens

Tokens · last 15 daysAug 21Sep 4

How it behaves under real clients

The same model answering different prompt shapes — measured, not benchmarked.

ClientRequestsTokensThroughputTo first tokenp95 totalCompleted
Python App181711.6K48 tok/s6.74 s132 s100%

Grouped by the client that sent the request. Not a benchmark: the same model on different prompt shapes. Throughput and time-to-first-token are medians; p95 is the slowest response in twenty. 2 clients under 100 requests not shown.

Two clocks, and why they disagree

Kyma measures this model twice. Both are real; they answer different questions.

Probe · every 6h · 30 days

3.58s to answer

One fixed prompt, on a schedule, to every model. Comparable, because the model is the only thing that changes.

Observations
700
Answered by a substitute
49

Real traffic · last 7 days

30.26s to answer

Your requests, at the lengths clients actually send. Not comparable between models, but it is what running this one feels like.

Requests
61
Completed
100%
p95
182.8 s

The gap is prompt length, not the model degrading. Use the probe figure to choose between models, the traffic figure to budget for your own.

Pricing

Pay per token. Cached input bills at this model’s own cached rate, listed below.

$0.0494 /1M input$0.2406 /1M output
Hobby10 req/day · 2K in / 500 out
~$0.07/mo
Production1,000 req/day · 2K in / 500 out
~$6.57/mo
Scale20,000 req/day · 2K in / 500 out
~$131/mo
+ Estimate your workload
1,000
2,000
500

Estimated monthly cost

$6.57

$0.2191 / day on GPT-OSS 120B

Same workload on:

GPT-5.6 Sol Pro$365+5445%
GPT-5.6 Sol$365+5445%

Estimates use list pricing. Actual bills depend on real token counts, and every response includes its exact cost.

When to use GPT-OSS 120B

Updated 2026-06-10

Where this model earns its cost — and where it doesn't.

GPT-OSS 120B is OpenAI's open-source model at 120B parameters, built for general intelligence and writing. On Kyma it sits in the strong quality tier with cheap-tier pricing — the combination teams pick when they need broadly capable output across many requests and the bill matters.

It has earned that role in production, mostly under coding agents and direct SDK integrations. Every call gets Kyma's automatic failover, and prompt caching is fully supported — repeated prompt prefixes bill at this model's cached input rate.

The 128K-token context window handles long documents and conversation history, while function calling and structured outputs make it usable inside agent pipelines, not just chat. It's text-in, text-out, with generations capped at 8K output tokens.

Writing and drafting

Its core strength — articles, summaries, rewrites, and editorial work at a price that holds up across high volume.

General assistants

A broadly capable default for chatbots and Q&A where you want strong-tier answers without flagship spend.

Agent pipelines

Function calling plus structured outputs keep it reliable inside multi-step agents — OpenClaw is already its top app by tokens on Kyma.

High-volume batch work

Cheap-tier pricing with prompt caching makes it economical for classification, extraction, and bulk text processing.

Long-context tasks

The 128K window fits substantial documents and long-running conversations in a single request.

Not ideal for: Image inputs (it's text-only), extended step-by-step reasoning modes (it has none), or single very long generations — output is capped at 8K tokens. Its medium speed also rules it out for latency-critical UX.

How it compares

Against the peers people actually weigh it against.

SpecGPT-OSS 120BGPT-5.6 Sol ProGPT-5.6 Sol
Input /1M$0.0494$2.70$2.70
Output /1M$0.2406$13.50$13.50
Context128K1M1M
ToolsYesYesYes
ReasoningNoYesYes
Throughput34.2 tok/s51.8 tok/s28.1 tok/s

Quick start

Up and running in under two minutes.

  1. 1

    Create an API key

    Sign up and grab a key from the dashboard — $0.50 free credit, no card required.

    Get API key →
  2. 2

    Make your first request

    Drop in your key and send a chat completion — fully OpenAI-compatible.

    curl https://kymaapi.com/v1/chat/completions \
      -H "Authorization: Bearer YOUR_API_KEY" \
      -H "Content-Type: application/json" \
      -d '{
        "model": "gpt-oss-120b",
        "messages": [
          {"role": "user", "content": "Explain prompt caching in one paragraph."}
        ]
      }'
  3. 3

    Stream responses

    Add "stream": true to receive tokens as they arrive.

    curl https://kymaapi.com/v1/chat/completions \
      -H "Authorization: Bearer YOUR_API_KEY" \
      -H "Content-Type: application/json" \
      -d '{
        "model": "gpt-oss-120b",
        "stream": true,
        "messages": [{"role": "user", "content": "Hello!"}]
      }'

FAQ

Common questions about this model.

What is the context window of GPT-OSS 120B?

GPT-OSS 120B has a 128K-token context window — roughly 188 pages of text in a single request.

How much does the GPT-OSS 120B API cost?

$0.0494 per 1M input tokens and $0.2406 per 1M output tokens. No subscription; you pay only for what you use.

Does GPT-OSS 120B support function calling?

Yes — GPT-OSS 120B supports tool/function calling and structured outputs (JSON mode), so it works with agent frameworks out of the box.

Are the weights for GPT-OSS 120B publicly available?

Yes. OpenAI publishes GPT-OSS 120B's weights as openai/gpt-oss-120b, so you can download and run the model yourself (https://huggingface.co/openai/gpt-oss-120b, read 2026-08-14). Kyma serves it because it is convenient and has failover behind it, not because it is the only way to reach it.

How do I use GPT-OSS 120B?

Kyma is OpenAI-compatible: point your SDK's base URL at https://kymaapi.com/v1, use your Kyma API key, and set the model to gpt-oss-120b. Signing up is free and includes $0.50 of credit — no card required.

Is GPT-OSS 120B good for writing?

Yes — writing is what it's recommended for on Kyma, alongside general-purpose work. It produces strong-tier prose at cheap-tier rates, which is why it handles high-volume drafting and rewriting workloads well. For tasks that need extended chain-of-thought reasoning, pick a reasoning-capable model instead.

What throughput should I expect?

It's a medium-speed model. That's comfortable for background jobs, batch processing, and agent steps, but if your product streams responses to users in real time, a fast-tier model will feel noticeably snappier.

Why use GPT-OSS 120B through Kyma?

One API key and one OpenAI-compatible endpoint covers this and every other model on the platform. You get automatic failover when a serving path degrades, prompt caching on repeated prefixes, exact per-request cost in usage.cost, and $0.50 of free credit at signup — no card required.

Start with $0.50 free credit — no card required.Create account →

More models by OpenAI

See all 12
ModelContextInputOutput
OpenAIGPT Transcribe$0.0061 / min
OpenAIGPT-5.6 Terra1M$2.70$16.20
OpenAIGPT-5.6 Luna1M$0.27$1.62
OpenAIGPT-5.6 Luna Pro1M$0.27$1.62
OpenAIGPT-5.6 Terra Pro1M$2.70$16.20
OpenAIGPT-5.6 Sol1M$2.70$13.50
OpenAIGPT-5.6 Sol Pro1M$2.70$13.50
OpenAIGPT Realtime Translate$0.0459 / min