n8n-code-python
Write Python in n8n Code nodes (native Python, language pythonNative, n8n 2.x). Use when the user explicitly wants Python in a Code node, when migrating old Pyodide/"Python (Beta)" code that used input/json/node/now, or when a Python Code node fails with NameError, "Security violations detected", "Import of standard library module … is disallowed", "buildclass not found", "A 'json' property isn't a dictionary", or "Python runner unavailable". Covers the only two variables (items/item), dict-only access, imports blocked by default, the sandbox's denied builtins, accepted return shapes, and how errors interact with onError. JavaScript is the default for Code nodes — native Python has no n8n helpers and, by default, no imports. EXCEPTION — for Python in the AI-agent-callable Custom Code Tool (@n8n/n8n-nodes-langchain.toolCode), use the n8n-code-tool skill instead (input is query, return must be a string).
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/czlonkowski/n8n-skills --skill n8n-code-python- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads n8n-code-python automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
Security audits
Independent scans of the skill's instructions and bundled files.
SKILL.md
The instructions your agent reads when the skill is triggered.
Python Code Node (native)
Since n8n 2.0 the Code node's Python runs as native Python in a task runner (language: "pythonNative"). The old Pyodide "Python (Beta)" is gone, and with it every n8n helper it had:
_input, _json, _node, _now, _today and _jmespath all raise NameError now. Code copied
from old templates, forum posts or older docs usually breaks on this.
JavaScript first — stronger than before
Native Python gives you two variables and plain Python, and by default no imports: no
json, datetime or re. Everything n8n-specific ($('Node'), $jmespath, Luxon,
this.helpers.httpRequest, static data) exists only in JavaScript. Use Python only when the user
explicitly asks for it. Even then, first check whether an expression, Edit Fields, or a native
node (Crypto, Date & Time, HTML, XML) does the job. See n8n-code-javascript and the transform
gatekeeper in n8n-expression-syntax.
Quick start
# Run Once for All Items (default mode)
return [
{"json": {"name": it["json"]["name"], "revenue": it["json"]["revenue"]}}
for it in _items
if it["json"].get("active")
]
# Run Once for Each Item
row = _item["json"]
return {"json": {**row, "name_upper": (row.get("name") or "").upper()}}
Node config: {"language": "pythonNative", "mode": "runOnceForAllItems" | "runOnceForEachItem", "pythonCode": "..."} on n8n-nodes-base.code typeVersion 2.
The only inputs: _items and _item
| Mode | Variable | Shape |
|---|---|---|
| Run Once for All Items | _items | list of plain dicts {"json": {...}, "pairedItem": {...}} |
| Run Once for Each Item | _item | one plain dict {"json": {...}, "pairedItem": {...}} |
- Each variable exists only in its own mode.
_itemsin each-item mode (or_itemin all-items mode) raisesNameError. - Dict access only.
it["json"]["name"]orit["json"].get("name").it.json.nameraisesAttributeError: 'dict' object has no attribute 'json'. - No other nodes. There is no
_node/$('Node')equivalent. If you need data from another branch, bring it in with Merge first, or read it in JavaScript. - Webhook payloads are under
["body"]:_items[0]["json"].get("body", {}).get("email"). - Binary data isn't covered here. Read and write binary in JavaScript (see n8n-binary-and-data).
- pairedItem: returning
_items/_itemkeeps it. When you build new dicts and downstream uses$('Node').item, add"pairedItem": {"item": i}to each returned item. That isn't verified on native Python yet, so test-run before relying on it. - Missing keys: prefer
.get(key, default).row["missing"]raisesKeyError.
Migration table for legacy code:
| Legacy (Pyodide) | Native |
|---|---|
_input.all() | _items |
_input.first()["json"] | _items[0]["json"] (guard if _items) |
_input.item / _json | _item / _item["json"] |
_node["X"] | not available: Merge upstream, or use JS |
_now, _today | not available: pass {{ $now.toISO() }} in via Edit Fields, or use JS |
_jmespath(data, q) | not available: $jmespath in an expression, or a comprehension |
item.json.field | item["json"]["field"] |
Imports: blocked by default
Every import (standard library and third-party) is checked against an allowlist before the
code runs. The default allowlist is empty, so even import json rejects the whole node:
Security violations detected
Line 1: Import of standard library module 'json' is disallowed. Allowed stdlib modules: none
- n8n Cloud: no imports at all.
- Self-hosted: the admin can allowlist modules in the task-runner config (see
n8n-self-hosting →
TASK_RUNNERS.md). Some instances therefore allowjson,datetimeandre, and most don't. - Default to import-free code. If an import would really help, confirm it first: a
one-line test node
import json+return [{"json": {"ok": True}}], or ask the user. Never assume. - Without imports: parse JSON strings upstream (
{{ JSON.parse($json.payload) }}in Edit Fields). Do date math with the Date & Time node or Luxon in an expression. ISO-8601 strings still compare and sort correctly as plain strings. Use the Crypto node for hashing. requests,pandasandnumpyare never available unless the admin built a custom runner image. Use the HTTP Request node for HTTP.
Sandbox limits (these fail even without imports)
| You write | What happens | Use instead |
|---|---|---|
eval, exec, compile, open, input, type, getattr, setattr, hasattr, vars, dir, globals, locals, object, memoryview, breakpoint | NameError: name 'type' is not defined (runtime) | isinstance(x, dict); key in d / d.get(key) |
class Foo: ... | __build_class__ not found (runtime) | dicts + functions |
x.__class__, "{0.__class__}".format(x), __import__("json") | Security violations detected (whole node rejected before running) | — |
global counter inside a function | NameError: name 'counter' is not defined, because your code runs inside a wrapper function | nonlocal counter |
Everything else in plain Python works (verified): comprehensions, generators, lambdas, closures,
recursion, try/except, f-strings / .format() / %, sorted/min/max/sum/any/all/
enumerate/zip/round, sets, isinstance, print() (output goes to the browser console).
Return shapes (verified)
Observed on n8n 2.38.5. The auto-wrapping and passthrough behaviours below are undocumented and could change in a later release. Re-check with a test run after upgrading n8n.
Run Once for All Items
| Return | Result |
|---|---|
[{"json": {...}}, ...] | canonical, N items |
[{...}, ...] (plain dicts) | auto-wrapped under json, N items |
{"json": {...}} or a single plain dict | 1 item |
_items (mutated in place) | passthrough with your changes |
None / no return | error Cannot read properties of null (reading 'json') |
Run Once for Each Item
| Return | Result |
|---|---|
{"json": {...}}, a plain dict, or _item | 1 item |
None | the item is dropped (a built-in filter) |
| a list | error A 'json' property isn't a dictionary [item 0] |
Value conversion on output: tuple becomes a list, set becomes the string "{1, 2}",
and a datetime becomes str(dt) ("2026-09-16 10:18:00.025792", not ISO). Convert explicitly
(sorted(s), dt.isoformat()).
Prefer the explicit [{"json": ...}] in all-items mode and {"json": ...} in each-item mode.
The auto-wrapping works, but the explicit shape makes the intent obvious to the next reader.
Errors and onError
A plain raise ValueError("bad row") fails the node with that message. When the node has an
onError continue mode, the three failure kinds behave differently (verified):
| Failure | continueErrorOutput | continueRegularOutput |
|---|---|---|
Runtime exception (raise, KeyError, NameError, denied builtin) | {"error": "<message>"} on the error output (main[1]) ✅ | {"error": "<message>"} on the main output |
Static rejection (Security violations detected: import, dunder) | node marked failed, but the input items, unchanged, go out the success output; main[1] stays empty | input items, unchanged, on the main output |
Bad return shape (list in each-item mode, None in all-items mode) | same: unchanged input on the success output | same |
The last two are silent-data traps: downstream nodes receive unprocessed input as if the code had run, and the execution still shows success. No error branch catches them. Prevent them (no imports unless confirmed, correct return shape) and confirm with a real test run, checking the Code node's status and output (see n8n-error-handling).
Other messages:
Python runner unavailable: Python 3 is missing from this system: the self-hosted instance has no Python task runner (the stock image ships none). It's an infrastructure problem, not a code problem. See n8n-self-hosting →TASK_RUNNERS.md.validate_node/validate_workflowcatch a few Python mistakes (import requests, missingreturn,return None). They do not catch_input/_json, dot access, blocked stdlib imports, dunder access or classes. A test execution is the only reliable check.
Performance
Each Python Code node costs roughly 0.4 s (about 1 s when the runner is cold), noticeably more than a JS Code node or an expression. Process lists in Run Once for All Items mode rather than per item, and don't chain several small Python nodes where one would do.
Checklist
- The user actually asked for Python. Otherwise JS, an expression, or a native node.
- Mode matches the variable:
_items(all items) /_item(each item). - Only dict access. No
_input,_json,_node,_nowor_jmespath. - No
importunless confirmed allowlisted on this instance. - No classes,
type(),getattr/hasattror dunders.nonlocalinstead ofglobal. - Return shape fits the mode. Sets and datetimes converted explicitly.
- Ran a real test execution and inspected the output items (validation alone won't catch the traps above).
Reference
- COMMON_PATTERNS.md: 12 import-free patterns, each verified on a live n8n instance (filter, aggregate, group, dedupe, top N, flatten, validate, drop items, text report, safe nested access, running totals, ISO timestamps).
Related skills
- n8n-code-javascript: the default for Code nodes, with all n8n helpers.
- n8n-expression-syntax:
$jmespath, Luxon and the transform gatekeeper, often a better fit than any Code node. - n8n-code-tool: Python in the AI-agent Custom Code Tool (
_query, returns a string). - n8n-error-handling: wiring error outputs; the passthrough trap above.
- n8n-self-hosting: enabling the Python task runner and allowlisting modules.
FAQ
What does the n8n-code-python skill do?
Write Python in n8n Code nodes (native Python, language pythonNative, n8n 2.x). Use when the user explicitly wants Python in a Code node, when migrating old Pyodide/"Python (Beta)" code that used input/json/node/now, or when a Python Code node fails with NameError, "Security violations detected", "Import of standard library module … is disallowed", "buildclass not found", "A 'json' property isn't a dictionary", or "Python runner unavailable". Covers the only two variables (items/item), dict-only access, imports blocked by default, the sandbox's denied builtins, accepted return shapes, and how errors interact with onError. JavaScript is the default for Code nodes — native Python has no n8n helpers and, by default, no imports. EXCEPTION — for Python in the AI-agent-callable Custom Code Tool (@n8n/n8n-nodes-langchain.toolCode), use the n8n-code-tool skill instead (input is query, return must be a string).
How do I install n8n-code-python?
Run npx skills add https://github.com/czlonkowski/n8n-skills --skill n8n-code-python in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/n8n-code-python/ (personal) or .claude/skills/n8n-code-python/ (project).
Which AI agents can use n8n-code-python?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is n8n-code-python safe to install?
Security partners have reviewed it: Gen Agent Trust Hub passed; Socket passed; Snyk passed; Runlayer flagged items to review; ZeroLeaks passed. As with any skill, read the SKILL.md and bundled scripts before installing.
Who maintains n8n-code-python?
It is published by czlonkowski in czlonkowski/n8n-skills. It has 4,868 recorded installs.
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