Save an app file

curl --request POST \
  --url https://app.base44.com/api/apps/{app_id}/coding/write \
  --header 'Content-Type: application/json' \
  --header 'api_key: <api-key>' \
  --data '
{
  "file_path": "src/pages/About.jsx",
  "content": "export default function About() {\n  return <h1>About</h1>;\n}\n"
}
'

import requests

url = "https://app.base44.com/api/apps/{app_id}/coding/write"

payload = {
    "file_path": "src/pages/About.jsx",
    "content": "export default function About() {
  return <h1>About</h1>;
}
"
}
headers = {
    "api_key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {api_key: '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    file_path: 'src/pages/About.jsx',
    content: 'export default function About() {\n  return <h1>About</h1>;\n}\n'
  })
};

fetch('https://app.base44.com/api/apps/{app_id}/coding/write', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://app.base44.com/api/apps/{app_id}/coding/write",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'file_path' => 'src/pages/About.jsx',
    'content' => 'export default function About() {
  return <h1>About</h1>;
}
'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "api_key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://app.base44.com/api/apps/{app_id}/coding/write"

	payload := strings.NewReader("{\n  \"file_path\": \"src/pages/About.jsx\",\n  \"content\": \"export default function About() {\\n  return <h1>About</h1>;\\n}\\n\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("api_key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://app.base44.com/api/apps/{app_id}/coding/write")
  .header("api_key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"file_path\": \"src/pages/About.jsx\",\n  \"content\": \"export default function About() {\\n  return <h1>About</h1>;\\n}\\n\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://app.base44.com/api/apps/{app_id}/coding/write")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["api_key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"file_path\": \"src/pages/About.jsx\",\n  \"content\": \"export default function About() {\\n  return <h1>About</h1>;\\n}\\n\"\n}"

response = http.request(request)
puts response.read_body

{
  "id": "6820f3a4e7b91d003c45a1f2",
  "name": "My CRM",
  "slug": "my-crm-3c45a1f2",
  "user_description": "A CRM to track leads and deals",
  "created_by": "developer@example.com",
  "created_date": "2026-08-01T09:15:00",
  "updated_date": "2026-08-02T14:30:00",
  "status": {
    "state": "ready",
    "details": "Publishing app",
    "request_id": "a1b2c3d4e5f67890abcdef12",
    "last_updated_date": "2026-08-02T14:30:00Z",
    "error_source": "build",
    "paywall_context": {
      "billing_organization_id": "67e0b12c4d8a3f005b21c9e4",
      "user_id": "6706af53b9c1e2004a37d85f",
      "evaluated_at": "2026-08-02T14:30:00Z"
    }
  },
  "last_deployed_at": "2026-08-02T14:30:00",
  "screenshot_url": "https://storage.base44.com/screenshots/6820f3a4e7b91d003c45a1f2.png",
  "preview_screenshot_url": "https://storage.base44.com/previews/6820f3a4e7b91d003c45a1f2.png"
}

Code

Save an app file

This API is in beta. Endpoints, fields, and behavior may still change, so avoid depending on it in production.

Saves a file into the app, the same way saving in the builder’s code editor does.

Base44 writes the file, applies it to the app, and takes care of what the path implies: a backend function is redeployed, an entity or agent schema is parsed and validated, and a change that affects row-level security records a revertible notice on the app’s chat.

Sending an empty content deletes the file. That is the builder’s own convention for this path, so treat an empty string as a delete rather than as a way to blank a file.

Paths are relative to the app root. Entity and agent schemas, workflows and email templates each have one canonical location, and a legacy shorthand is refused with a 400 naming the canonical form. A path that escapes the app is refused the same way.

Writing a backend function deploys it, so the request takes as long as the deploy and answers 422 carrying the compiler’s diagnostics when the code doesn’t build. Backend functions also need a Builder plan or higher on the app’s workspace. Use Save several app files to write a batch of frontend files in one call.

The response is the app document as it stands after the change, the same shape Get app returns.

This endpoint accepts a personal API key. Workspace API keys are not authorized for it and are rejected with a 403.

The response includes fields beyond the ones documented here. Don’t rely on undocumented response fields, as they can change at any time. Send only the fields documented here. Other request fields are not supported and their behavior can change.

POST

api

apps

{app_id}

coding

write

Save an app file

curl --request POST \
  --url https://app.base44.com/api/apps/{app_id}/coding/write \
  --header 'Content-Type: application/json' \
  --header 'api_key: <api-key>' \
  --data '
{
  "file_path": "src/pages/About.jsx",
  "content": "export default function About() {\n  return <h1>About</h1>;\n}\n"
}
'

import requests

url = "https://app.base44.com/api/apps/{app_id}/coding/write"

payload = {
    "file_path": "src/pages/About.jsx",
    "content": "export default function About() {
  return <h1>About</h1>;
}
"
}
headers = {
    "api_key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {api_key: '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    file_path: 'src/pages/About.jsx',
    content: 'export default function About() {\n  return <h1>About</h1>;\n}\n'
  })
};

fetch('https://app.base44.com/api/apps/{app_id}/coding/write', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://app.base44.com/api/apps/{app_id}/coding/write",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'file_path' => 'src/pages/About.jsx',
    'content' => 'export default function About() {
  return <h1>About</h1>;
}
'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "api_key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://app.base44.com/api/apps/{app_id}/coding/write"

	payload := strings.NewReader("{\n  \"file_path\": \"src/pages/About.jsx\",\n  \"content\": \"export default function About() {\\n  return <h1>About</h1>;\\n}\\n\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("api_key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://app.base44.com/api/apps/{app_id}/coding/write")
  .header("api_key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"file_path\": \"src/pages/About.jsx\",\n  \"content\": \"export default function About() {\\n  return <h1>About</h1>;\\n}\\n\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://app.base44.com/api/apps/{app_id}/coding/write")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["api_key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"file_path\": \"src/pages/About.jsx\",\n  \"content\": \"export default function About() {\\n  return <h1>About</h1>;\\n}\\n\"\n}"

response = http.request(request)
puts response.read_body

{
  "id": "6820f3a4e7b91d003c45a1f2",
  "name": "My CRM",
  "slug": "my-crm-3c45a1f2",
  "user_description": "A CRM to track leads and deals",
  "created_by": "developer@example.com",
  "created_date": "2026-08-01T09:15:00",
  "updated_date": "2026-08-02T14:30:00",
  "status": {
    "state": "ready",
    "details": "Publishing app",
    "request_id": "a1b2c3d4e5f67890abcdef12",
    "last_updated_date": "2026-08-02T14:30:00Z",
    "error_source": "build",
    "paywall_context": {
      "billing_organization_id": "67e0b12c4d8a3f005b21c9e4",
      "user_id": "6706af53b9c1e2004a37d85f",
      "evaluated_at": "2026-08-02T14:30:00Z"
    }
  },
  "last_deployed_at": "2026-08-02T14:30:00",
  "screenshot_url": "https://storage.base44.com/screenshots/6820f3a4e7b91d003c45a1f2.png",
  "preview_screenshot_url": "https://storage.base44.com/previews/6820f3a4e7b91d003c45a1f2.png"
}

Authorizations

api_key

string

header

required

Personal API key.

Path Parameters

app_id

string

required

ID of the app whose code to change.

Body

application/json

file_path

string

required

Path of the file, relative to the app root.

content

string

required

Full contents to save. An empty string deletes the file, which is this endpoint's convention rather than a way to blank one.

Response

The app after the write.

An app in a workspace, limited to the properties the caller requested.

string | null

ID of the app.

Example:

"6820f3a4e7b91d003c45a1f2"

name

string | null

Display name of the app.

Example:

"My CRM"

slug

string | null

URL slug for the app, auto generated from the name and app ID or set to a custom value, or null if the app has no slug yet. The published URL is built from it.

Example:

"my-crm-3c45a1f2"

user_description

string | null

Description of the app, or null if none was set. On a newly created app this holds the original prompt text.

Example:

"A CRM to track leads and deals"

created_by

string | null

Email of the user who created the app.

Example:

"developer@example.com"

created_date

string<date-time> | null

Time the app was created, as a UTC timestamp in ISO 8601 format.

Example:

"2026-08-01T09:15:00"

updated_date

string<date-time> | null

Time the app document was last written, as a UTC timestamp in ISO 8601 format.

Example:

"2026-08-02T14:30:00"

status

AppStatusResponse · object | null

The app's current build status. Poll while a build is in progress to watch it finish. This tracks building, not publishing.

Show child attributes

last_deployed_at

string<date-time> | null

Time the app was last published, as a UTC timestamp in ISO 8601 format, or null if it has never been published.

Example:

"2026-08-02T14:30:00"

screenshot_url

string | null

URL of a screenshot of the published app. Captured shortly after each publish, so it can briefly lag or be null right after publishing.

Example:

"https://storage.base44.com/screenshots/6820f3a4e7b91d003c45a1f2.png"

preview_screenshot_url

string | null

URL of a preview screenshot taken before publishing, distinct from screenshot_url, or null if none has been captured.

Example:

"https://storage.base44.com/previews/6820f3a4e7b91d003c45a1f2.png"

Base44 APIs

Apps API (Beta)

Monitoring API

Audit Logs API

Save an app file

Authorizations

Path Parameters

Body

Response