aer 1.0

aer 1.0 was released on May 26, 2026. It is the first general release of the Apex Execution Runtime, a local Apex runtime for Salesforce developers that runs, tests, and debugs Apex on your own machine and serves a Salesforce-compatible API, with no org and no deployment.

Apex development normally involves an expensive feedback loop: change the code, deploy to an org, wait for compilation, run tests remotely, and read the logs. aer 1.0 replaces that loop with a local binary.

Fast local Apex tests

aer reads your Apex and the metadata next to it, builds a local schema, and executes your tests without deploying anything. The test runner supports:

• @IsTest classes and methods, Test.startTest() and Test.stopTest(), and test data isolation
• HttpCalloutMock for callouts
• Watch mode with --watch, which re-runs affected tests as files change
• JSONL and JUnit XML test results, and Cobertura or JSON code coverage
• Loading managed and first-party packages with --package, and schema generation from metadata
• CI runs through the octoberswimmer/aer-dist GitHub Action

Runtime coverage

The runtime models the parts of Apex that normally require an org:

• Apex classes and triggers, SObjects, SOQL, and DML
• Collections, control flow, exceptions, and switch statements
• JSON, HTTP, Crypto, date and time, XML, DOM, URL, and approval APIs
• DataWeave script execution
• External Services alongside HttpCalloutMock
• Standard and custom object metadata, including record types, picklists, field sets, and describe information
• More than 30 standard namespaces, including System, Database, Schema, Messaging, Metadata, ConnectApi, and the commerce and industry cloud namespaces

Interactive debugging

The aer Local Apex Debugger extension for VS Code lets you set breakpoints, step through Apex, inspect variables, and evaluate expressions in the Debug Console. aer test --debug installs the extension the first time it runs and opens VS Code ready to start:

aer test --debug ./force-app --filter OrderService_Test

See Interactive Debugging.

Local development server

aer server runs a local server that loads your Apex, LWC, flows, and object metadata:

aer server ./force-app
aer server ./force-app --watch

The server provides:

• Lightning Web Component preview at http://127.0.0.1:8080/dev/lwc
• An application explorer showing objects, fields, relationships, and Apex signatures
• Salesforce-compatible REST and SOAP APIs, so the Salesforce CLI and other tools can be pointed at the local server
• An event viewer and platform event publishing
• Managed package loading, sandbox mode, permission set assignment, real callouts, and WireMock stubs for integration testing

See Development Server.

Apex language server

aer includes a Language Server Protocol implementation with code completion, go to definition, find references, hover information, document symbols, and formatting. It is used by the VS Code extension and works with other LSP-compatible editors.

Integrations

• VS Code, through the aer Local Apex Debugger extension
• IntelliJ, through Illuminated Cloud
• Salesforce CLI, through the @octoberswimmer/aer-sf-plugin plugin
• Zed, through the Salesforce extension

Installation

brew install octoberswimmer/tap/aer

Or try aer in the browser without installing anything at the VS Code Web Demo.