# glm-5.3 — API, Pricing & Context Window | Vivgrid

> Source: https://vivgrid.com/docs/models/glm-5.3

glm-5.3 on Vivgrid: Zhipu AI's coding and long-horizon agent model with a 1M-token context window, function calling, and competitive pricing.

`glm-5.3` is Zhipu AI's newest coding model. It keeps the `glm-5.2` base model and 1M-token context window, and puts its gains into post-training: better long-horizon agent behaviour, more reliable multi-step tool use, and stronger results on coding benchmarks — at the same price as `glm-5.2`.

On Vivgrid, `glm-5.3` is reachable through the unified, OpenAI-compatible endpoint, so it integrates cleanly alongside models from OpenAI, Anthropic, Google, and DeepSeek under one API key.

## Specifications

| Field | Value |
| --- | --- |
| Provider | Zhipu AI |
| Model ID | `glm-5.3` |
| Best for | Coding |
| Available on | Vibe coding, Chat Completions |
| Context window | 1,000,000 tokens |
| Max output | 128,000 tokens |
| Modalities | Text |
| Tool / function calling | Yes |
| Knowledge cutoff | 2026-06 |
| Acceleration | Global (centralized) |

## Pricing

Pricing in USD per 1M tokens.

| Input | Cached input | Output |
| --- | --- | --- |
| $1.20 | $0.30 | $4.20 |

### What one request costs

The rates above applied to a 20K-token prompt with a 2K-token reply — a typical single agent turn, small enough that every request is billed at the base rate.

| Request | Cost |
| --- | --- |
| Cold prompt, nothing cached | $0.0324 |
| Warm prompt, 90% of the input served from cache | $0.0162 |


## Use glm-5.3 in your coding agent

`glm-5.3` works with the same Vivgrid key and `https://api.vivgrid.com/v1` endpoint as every other model in the catalog. Grab your API key from the [Vivgrid Console](https://console.vivgrid.com), then drop one of the configurations below into your agent of choice.

### OpenCode

[OpenCode](https://opencode.ai) has Vivgrid built in, so you can use `glm-5.3` without writing any config: open `/models`, search for `vivgrid`, paste your API key and pick the model. The [OpenCode tutorial](/docs/tutorials/opencode) walks through it step by step.

Prefer to configure it by hand? Install OpenCode:

```bash
npm i -g opencode-ai
```

Declare `glm-5.3` under the Vivgrid provider in your global OpenCode config, `~/.config/opencode/opencode.json`. The `@ai-sdk/openai-compatible` provider talks to Vivgrid over **Chat Completions** (`/v1/chat/completions`):

```json title="~/.config/opencode/opencode.json" lines icon="json" highlight={3,6,9,10}
{
  "$schema": "https://opencode.ai/config.json",
  "model": "vivgrid/glm-5.3",
  "provider": {
    "vivgrid": {
      "npm": "@ai-sdk/openai-compatible",
      "name": "Vivgrid",
      "options": {
        "baseURL": "https://api.vivgrid.com/v1",
        "apiKey": "{env:VIVGRID_API_KEY}"
      },
      "models": {
        "glm-5.3": {
          "name": "glm-5.3",
          "tool_call": true,
          "modalities": { "input": ["text"], "output": ["text"] },
          "limit": { "context": 1000000, "output": 128000 }
        }
      }
    }
  }
}
```

Export your key and launch OpenCode:

```bash
export VIVGRID_API_KEY="viv-xxxxxxxxxxxxx"
opencode
```

Use `/models` to switch between `glm-5.3` and other Vivgrid models mid-session. See the full [OpenCode tutorial](/docs/tutorials/opencode).

### Pi

Install [Pi](https://pi.dev):

```bash
npm install -g --ignore-scripts @earendil-works/pi-coding-agent
```

Add `glm-5.3` to the Vivgrid provider in `~/.pi/agent/models.json`. Pi talks to Vivgrid over **Chat Completions** (`/v1/chat/completions`):

```json title="~/.pi/agent/models.json" lines icon="json" highlight={4,5,12}
{
  "providers": {
    "vivgrid": {
      "baseUrl": "https://api.vivgrid.com/v1",
      "apiKey": "viv-xxxxxxxxxxxxx",
      "api": "openai-completions",
      "compat": {
        "sendSessionAffinityHeaders": true
      },
      "models": [
        {
          "id": "glm-5.3",
          "input": ["text"],
          "contextWindow": 1000000,
          "maxTokens": 128000
        }
      ]
    }
  }
}
```

Make it the model Pi starts with in `~/.pi/agent/settings.json`:

```json title="~/.pi/agent/settings.json" lines icon="json" highlight={2,3}
{
  "defaultProvider": "vivgrid",
  "defaultModel": "glm-5.3"
}
```

Then verify and start Pi:

```bash
pi --list-models vivgrid
pi
```

Or run a one-shot prompt without entering the TUI:

```bash
pi -p "explain the auth flow in this repo" --model vivgrid/glm-5.3
```

See the full [Pi tutorial](/docs/tutorials/pi).

## API surfaces

The Vivgrid Console catalogs `glm-5.3` on 2 surfaces, all behind the same API key. The endpoint shown is the one the Console previews for that surface.

| Surface | Primary endpoint | Use it for |
| --- | --- | --- |
| Vibe coding | `/chat/completions` | Coding CLIs and IDE agents that drive the model themselves — point the tool at Vivgrid and keep your own loop. |
| Chat Completions | `/chat/completions` | Agent projects, where Vivgrid injects the model, system prompt and tools server-side, and Model API calls that name the model per request. |

## Quick start

Get an API key from the Vivgrid Console (https://console.vivgrid.com), then call `glm-5.3` directly.

```bash
curl https://api.vivgrid.com/v1/chat/completions \
  -H "Authorization: Bearer $VIVGRID_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "glm-5.3",
    "messages": [
      { "role": "user", "content": "Say hello in English, Chinese and Spanish." }
    ],
    "stream": true
  }'
```

## Choosing within the GLM 5.3 family

Prices are USD per 1M tokens at the base rate.

| Model | Context | Max output | Input | Output |
| --- | --- | --- | --- | --- |
| `glm-5.3` (this page) | 1,000,000 | 128,000 | $1.20 | $4.20 |
| [`glm-5.3-flash`](/docs/models/glm-5.3-flash) | 1,000,000 | 384,000 | $0.15 | $0.50 |


## Ideal use cases

- Long-horizon coding agents that chain many tool calls
- Whole-repository reasoning within a 1M-token context
- Cost-effective drop-in upgrade from `glm-5.2` at identical pricing
- Teams diversifying beyond US-based providers

## Related models

- [gpt-6-astra](/docs/models/gpt-6-astra) — OpenAI's frontier gpt-6 coding model
- [glm-5.2](/docs/models/glm-5.2) — same base model and price, prior post-training
- [kimi-k3](/docs/models/kimi-k3) — alternative frontier coding model with a 1M context