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Execute Python and TypeScript code inside a sandbox with stateful sessions, rich output, and streaming.

Execute code inside a running sandbox. The interpreter keeps a persistent REPL process alive so that variables, imports, and working directory survive across calls. Send code, get back stdout, stderr, rich results (text, images, HTML, JSON), and structured errors. For a full endpoint reference, see the Code Interpreter API.

Two runtimes are available:

Alias	Runtime	Notes
`python`, `py`, `python3`	Python 3.12	50+ pre-installed data-science packages. Matplotlib charts auto-captured as PNG and SVG.
`typescript`, `ts`, `javascript`, `js`, `bun`, `node`	Bun v1.3.10 (TypeScript)	Last expression is returned as a result. State accumulates across calls.

Create a context

from leap0 import DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client

client = Leap0Client()
sandbox = client.sandboxes.create(template_name=DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME)
context = sandbox.code_interpreter.create_context(
    language="python",
    cwd="/home/user",
)

print(context.id, context.language)

import { DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client } from "leap0";

const client = new Leap0Client();
const sandbox = await client.sandboxes.create({
  templateName: DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME,
});
const context = await sandbox.codeInterpreter.createContext("python", "/home/user");

console.log(context.id, context.language);
await client.close();

Field	Type	Required	Description
`language`	string	Yes	One of the supported language aliases.
`cwd`	string	No	Initial working directory. Defaults to `/home/user`.

List contexts

from leap0 import DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client

client = Leap0Client()
sandbox = client.sandboxes.create(template_name=DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME)
for context in sandbox.code_interpreter.list_contexts():
    print(context.id, context.language, context.cwd)

import { DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client } from "leap0";

const client = new Leap0Client();
const sandbox = await client.sandboxes.create({
  templateName: DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME,
});

for (const context of await sandbox.codeInterpreter.listContexts()) {
  console.log(context.id, context.language, context.cwd);
}

await client.close();

Get a context

from leap0 import DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client

client = Leap0Client()
sandbox = client.sandboxes.create(template_name=DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME)
context = sandbox.code_interpreter.get_context("<context_id>")
print(context)

import { DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client } from "leap0";

const client = new Leap0Client();
const sandbox = await client.sandboxes.create({
  templateName: DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME,
});
const context = await sandbox.codeInterpreter.getContext("<context_id>");

console.log(context);
await client.close();

Delete a context

from leap0 import DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client

client = Leap0Client()
sandbox = client.sandboxes.create(template_name=DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME)
sandbox.code_interpreter.delete_context("<context_id>")

import { DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client } from "leap0";

const client = new Leap0Client();
const sandbox = await client.sandboxes.create({
  templateName: DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME,
});

await sandbox.codeInterpreter.deleteContext("<context_id>");
await client.close();

Execute code

Run code synchronously. The sandbox waits for the code to finish and returns the full result in one response.

from leap0 import DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client

client = Leap0Client()
sandbox = client.sandboxes.create(template_name=DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME)

first = sandbox.code_interpreter.execute(
    code="prices = [10, 20, 30, 40, 50]",
    language="python",
)

second = sandbox.code_interpreter.execute(
    code="sum(prices) / len(prices)",
    language="python",
    context_id=first.context_id,
)

for item in second.items:
    if item.text:
        print(item.text)

import { DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client } from "leap0";

const client = new Leap0Client();
const sandbox = await client.sandboxes.create({
  templateName: DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME,
});

const first = await sandbox.codeInterpreter.execute({
  code: "prices = [10, 20, 30, 40, 50]",
  language: "python",
});

const second = await sandbox.codeInterpreter.execute({
  code: "sum(prices) / len(prices)",
  language: "python",
  contextId: first.contextId,
});

for (const item of second.items) {
  if (item.text) console.log(item.text);
}

await client.close();

Request fields

Field	Type	Required	Default	Description
`code`	string	Yes		Source code to execute.
`language`	string	No	`python`	Any supported alias.
`context_id`	string	No	auto-generated	Reuse an existing session.
`timeout_ms`	integer	No	`30000`	Max execution time in milliseconds.

Stream execution

Execute code and receive output line-by-line as Server-Sent Events. Use this for long-running scripts or anything where you want to show progress to the user before the process exits.

from leap0 import DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client

client = Leap0Client()
sandbox = client.sandboxes.create(template_name=DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME)
for event in sandbox.code_interpreter.execute_stream(
    code="""import time
for i in range(5):
print(f'Step {i}')
time.sleep(1)""",
    language="python",
    timeout_ms=60000,
):
    if event.type == "stdout":
        print(event.data)
    elif event.type == "exit":
        print(f"Done (exit code {event.code})")

import { DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client } from "leap0";

const client = new Leap0Client();
const sandbox = await client.sandboxes.create({
  templateName: DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME,
});

for await (const event of sandbox.codeInterpreter.executeStream({
  code:
    "import time\n" +
    "for i in range(5):\n" +
    " print(f'Step {i}')\n" +
    " time.sleep(1)",
  language: "python",
  timeoutMs: 60000,
})) {
  if (event.type === "stdout") console.log(event.data);
  if (event.type === "exit") console.log("Done (exit code " + event.code + ")");
}

await client.close();

Event types

Each data: line in the SSE stream is a JSON object:

Type	Fields	Meaning
`stdout`	`data`	A line printed to standard output.
`stderr`	`data`	A line printed to standard error.
`exit`	`code`	Process finished. `code` is `0` on success.
`error`	`data`	Interpreter-level failure (e.g. `"timeout"`).

Example stream for print("hello"):


data: {"type":"stdout","data":"hello"}

data: {"type":"exit","code":0}

Generating charts

Python's matplotlib is pre-installed and patched to automatically capture figures. Call plt.show() and the PNG and SVG representations appear in the items array - no file I/O required.

from leap0 import DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client

client = Leap0Client()
sandbox = client.sandboxes.create(template_name=DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME)
result = sandbox.code_interpreter.execute(
    code="""import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 2 * np.pi, 100)
plt.figure(figsize=(8, 4))
plt.plot(x, np.sin(x), label='sin(x)')
plt.plot(x, np.cos(x), label='cos(x)')
plt.legend()
plt.title('Trigonometric Functions')
plt.show()""",
    language="python",
)

for item in result.items:
    if item.png:
        print(f"PNG image: {len(item.png)} base64 chars")
    if item.svg:
        print(f"SVG image: {len(item.svg)} chars")

import { DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME, Leap0Client } from "leap0";

const client = new Leap0Client();
const sandbox = await client.sandboxes.create({
  templateName: DEFAULT_CODE_INTERPRETER_TEMPLATE_NAME,
});

const result = await sandbox.codeInterpreter.execute({
  code:
    "import matplotlib.pyplot as plt\n" +
    "import numpy as np\n\n" +
    "x = np.linspace(0, 2 * np.pi, 100)\n" +
    "plt.figure(figsize=(8, 4))\n" +
    "plt.plot(x, np.sin(x), label='sin(x)')\n" +
    "plt.plot(x, np.cos(x), label='cos(x)')\n" +
    "plt.legend()\n" +
    "plt.title('Trigonometric Functions')\n" +
    "plt.show()",
  language: "python",
});

for (const item of result.items) {
  if (item.png) console.log("PNG image:", item.png.length, "base64 chars");
  if (item.svg) console.log("SVG image:", item.svg.length, "chars");
}

await client.close();

Pre-installed Python packages

The Python runtime ships with these packages ready to import:

Category	Packages
Data science	numpy, pandas, scipy, scikit-learn, sympy
Visualization	matplotlib, seaborn, plotly, bokeh, kaleido
Image processing	pillow, opencv-python, scikit-image, imageio
Audio	librosa, soundfile
HTTP / Web	requests, aiohttp, beautifulsoup4, urllib3
Data formats	orjson, openpyxl, xlrd, python-docx
Scientific computing	numba, xarray
NLP	nltk, gensim, spacy, textblob
Utilities	pytz, joblib, pytest

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