> ## Documentation Index
> Fetch the complete documentation index at: https://docs.unifically.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Gemini 4 Hydrogen

> Google's Gemini 4 Hydrogen language model. See supported inputs, parameters, pricing, response fields, and API examples.

Gemini 4 Hydrogen is Google's fast Gemini 4 model for everyday coding and agent work, released on November 12, 2026. It accepts text and image input with a 1M-token window shared by input and output, and returns up to 64K output tokens per response. Reasoning effort is tunable with `reasoning_effort` set to `low`, `medium`, `high`, or `xhigh`. Thinking tokens are billed as output tokens. A reply at `xhigh` can take a minute or more to start, so stream the response and set client timeouts with headroom.

Try it in the browser: [Gemini 4 Hydrogen API playground](https://unifically.com/models/gemini-4-hydrogen).

## Model

```
google/gemini-4-hydrogen
```

| | |
| - | - |
| **Provider** | Google |
| **Name** | Gemini 4 Hydrogen |

## Supported Endpoints

* [Chat Completions](https://docs.unifically.com/api-reference/v1-chat-completions.md) — `POST /v1/chat/completions`

> [!CAUTION]
>
> **Send LLM requests to `https://direct-api.unifically.com`, not `https://api.unifically.com`.** The main host sits behind Cloudflare, and Cloudflare's proxy timeout cuts most LLM requests short before the model has finished writing. When that happens you receive a truncated reply and are still charged for every token generated up to the cut-off. `direct-api.unifically.com` reaches the same API without the Cloudflare proxy, so long responses complete in full.

## Example

```bash theme={null}
curl -X POST https://direct-api.unifically.com/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "google/gemini-4-hydrogen",
    "reasoning_effort": "high",
    "stream": true,
    "messages": [
      {"role": "user", "content": "Find the bug in this function, explain it in two sentences, and write the fix."}
    ]
  }'
```

## Reasoning Effort

| Value | When to use it |
| - | - |
| `low` | Quick steps: classification, extraction, short summaries |
| `medium` | Routine coding and tool calls |
| `high` | Multi-step agent work and harder coding tasks |
| `xhigh` | The hardest reasoning. Slowest to start and uses the most output tokens |

## Image Input

Send an image in an `image_url` content part alongside your text, either as a direct https link or inline as a base64 data URI.

```bash theme={null}
curl -X POST https://direct-api.unifically.com/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "google/gemini-4-hydrogen",
    "messages": [
      {"role": "user", "content": [
        {"type": "text", "text": "Read every number in this chart and return them as a JSON table."},
        {"type": "image_url", "image_url": {"url": "https://example.com/chart.png"}}
      ]}
    ]
  }'
```

| | |
| - | - |
| **Accepted shape** | `image_url` part with a direct https link or a `data:image/...;base64` URI |
| **Links** | Must point straight at the image file, with no redirect, up to 14 MB. A link that cannot be downloaded returns `400` with the reason |
| **Billing** | Counted as input tokens at the model's input rate. The `usage.prompt_tokens` field shows the total |

> [!NOTE]
>
> **Volume discounts** are available for almost all models. Reach out at [contact@unifically.com](mailto:contact@unifically.com) to discuss custom pricing.


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