# Grok Build 0.1 vs GPT-5.3 Codex Spark

> Markdown mirror of https://router.one/models/compare/grok-build-0-1-vs-gpt-5-3-codex-spark for AI assistants and crawlers. Router One is an OpenAI-compatible LLM API gateway.

The listed rates and 1M-input + 1M-output workload example use base tiers, assuming every request meets: grok-build-0.1: request input ≤ 200,000 tokens. Requests above a threshold use the long-context rates below. Grok Build 0.1 is the lower-priced of the two on Router One — about 69% less on a 1M-input + 1M-output mix. Grok Build 0.1 offers 500K of context vs 400K for GPT-5.3 Codex Spark. Grok Build 0.1 answers on /v1/chat/completions; GPT-5.3 Codex Spark on /v1/chat/completions and /v1/responses (Codex CLI).

Grok Build 0.1 and GPT-5.3 Codex Spark compared on current per-token rates, context window, and capabilities — both callable through one OpenAI-compatible endpoint with per-request cost traces.

## Grok Build 0.1 vs GPT-5.3 Codex Spark: rates, context window, and capabilities

| Spec | Grok Build 0.1 | GPT-5.3 Codex Spark |
| --- | --- | --- |
| Input / 1M tokens | $0.40 | $0.4314 |
| Output / 1M tokens | $0.80 | $3.4521 |
| Cached input / 1M tokens | $0.08 | $0.04314 |
| Context window | 500K | 400K |
| Detail page | [Grok Build 0.1](https://router.one/models/grok-build-0-1) | [GPT-5.3 Codex Spark](https://router.one/models/gpt-5-3-codex-spark) |

grok-build-0.1: request input ≤ 200,000 tokens: Input $0.40 / 1M tokens, Output $0.80 / 1M tokens, Cache write $0.40 / 1M tokens, Cached input $0.08 / 1M tokens; request input > 200,000 tokens: Input $0.80 / 1M tokens, Output $1.60 / 1M tokens, Cache write $0.80 / 1M tokens, Cached input $0.16 / 1M tokens. The total input tokens in each request select the tier; its rates apply to the whole request, not only tokens above the threshold.

## What does 1M tokens cost on Grok Build 0.1 vs GPT-5.3 Codex Spark?

The listed rates and 1M-input + 1M-output workload example use base tiers, assuming every request meets: grok-build-0.1: request input ≤ 200,000 tokens. Requests above a threshold use the long-context rates below. For a workload of 1M input plus 1M output tokens at current rates: Grok Build 0.1 comes to $1.20, GPT-5.3 Codex Spark comes to $3.8835 — Grok Build 0.1 is about 69% cheaper on this mix. Real workloads skew heavily toward input tokens, so weigh the input rate by your own ratio; the cached-input row above is the posted catalog rate for that model.

## Switch between Grok Build 0.1 and GPT-5.3 Codex Spark without changing code

Both models are behind the same OpenAI-compatible endpoint, so an A/B test is a one-string change — same key, same code, and every request traced with tokens, cost, and latency in the dashboard:

`compare.sh`

```bash
curl https://api.router.one/v1/chat/completions \
  -H "Authorization: Bearer sk-your-router-one-key" \
  -H "Content-Type: application/json" \
  -d '{"model": "grok-build-0.1", "messages": [{"role": "user", "content": "Hello"}]}'

# Same request, other model — change one string:
#   "model": "openai/gpt-5.3-codex-spark"
```

## FAQ

### Is Grok Build 0.1 cheaper than GPT-5.3 Codex Spark?

The listed rates and 1M-input + 1M-output workload example use base tiers, assuming every request meets: grok-build-0.1: request input ≤ 200,000 tokens. Requests above a threshold use the long-context rates below. Input: Grok Build 0.1 $0.40 vs GPT-5.3 Codex Spark $0.4314 / 1M tokens; Grok Build 0.1 has the lower rate. Output: Grok Build 0.1 $0.80 vs GPT-5.3 Codex Spark $3.4521 / 1M tokens; Grok Build 0.1 has the lower rate. Total cost depends on the workload's input, output and cache usage. grok-build-0.1: request input ≤ 200,000 tokens: Input $0.40 / 1M tokens, Output $0.80 / 1M tokens, Cache write $0.40 / 1M tokens, Cached input $0.08 / 1M tokens; request input > 200,000 tokens: Input $0.80 / 1M tokens, Output $1.60 / 1M tokens, Cache write $0.80 / 1M tokens, Cached input $0.16 / 1M tokens. The total input tokens in each request select the tier; its rates apply to the whole request, not only tokens above the threshold. Rates change; the /models page is the live source of truth.

### Can I switch between Grok Build 0.1 and GPT-5.3 Codex Spark without changing code?

Yes. Both are served through the same OpenAI-compatible endpoint, so switching is changing the model string in the request — the key, base URL, and request shape stay identical.

### Where do these numbers come from?

Specs and prices on this page render from the live Router One catalog — the same data as the /models page — and refresh with it. Pricing methodology is documented on /pricing-methodology. Rates on this page were read from the live catalog on 2026-09-07 (UTC) and refresh within the hour.

## More comparisons

- [GPT-5.3 Codex Spark vs Claude Sonnet 5](https://router.one/models/compare/gpt-5-3-codex-spark-vs-claude-sonnet-5)

## See also

- Canonical page: https://router.one/models/compare/grok-build-0-1-vs-gpt-5-3-codex-spark
- All model comparisons: https://router.one/models/compare
- All models & prices: https://router.one/models (markdown: https://router.one/models.md)
- Pricing: https://router.one/pricing
- Grok API in China: https://router.one/grok-api-china
- GPT API access: https://router.one/cheap-gpt-api
- Cost calculator: https://router.one/llm-cost-calculator
- Pricing methodology: https://router.one/pricing-methodology