We check Slack's changelog and OpenAPI spec every day, because we run production integrations on the Slack API. This page lists the 123 changes we have recorded since monitoring started on 26 March 2026, newest first.
Our last successful check was on 4 October 2026. We are on it; until then this page may miss the newest changes.
4 breaking changes and 2 deprecations in the Slack API in the last 90 days. The latest: “Assistant messaging experience (assistant_view) deprecation” (20 August 2026).
Labels are assigned automatically. Check the vendor's note before planning work around an entry.
Slack CLI v4.8.0: New CLI features including manifest sync command, --manifest-source flag, code_channels support, and bug fixes for interactive prompts.
Slack Marketplace app submissions now require minimum 10 active workspace installations, increased from temporary lower threshold.
Slack CLI v4.7.0: New Slack CLI version adds app request status checking command, custom app icon support, and fixes help template display of hidden subcommands.
Slack CLI v4.7.0: Added app request status command, custom app icons support, and improved help template for Slack CLI.
New feature allowing agents and people to collaborate in dedicated channels with code diffs, Block Kit views, HTML previews, and Canvases for shared artifact work.
The assistant_view messaging experience will be deprecated in February 2027 and replaced by the new Agent Sessions API with agents.sessions.setStatus and agents.sessions.rename methods.
Affects one of your integrations? We take over the migration, at a fixed priceApps now receive agent_session_stopped event when users stop an agent stream, enabling proper handling of agent termination.
Assistant messaging experience (assistant_view) will be deprecated in February 2027, replaced by new Agent Sessions API with agents.sessions.setStatus and agents.sessions.rename methods.
Affects one of your integrations? We take over the migration, at a fixed priceNew Slack MCP and Skills Plugin for Claude Code and Cursor with AI-focused skills and direct Slack workspace interaction capabilities.
Slack CLI v4.6.0: Added slack manifest diff command to show differences between project manifest and app settings, and slack blocks preview command for Block Kit Builder.
Slack CLI v4.6.0: Added manifest diff command and Block Kit Builder preview command to Slack CLI.
Slack CLI v4.5.0: Added category flag to docs search, improved non-TTY error messages for prompts, fixed JSON parsing errors from empty files, and reduced verbose output.
Slack CLI v4.5.0: Added Claude Code plugin recommendation, reduced verbose output, new --category flag for docs search, and improved error messages.
Bolt for JS v5: Major version bump requiring Node.js 20+, removes Workflow Steps from Apps, migrates from axios to Fetch API, removes deprecated proxy/TLS configuration options.
Affects one of your integrations? We take over the migration, at a fixed priceBolt for JS v5 - Node.js 20+ requirement: Bolt for JS v5 requires Node.js 20+, removes Workflow Steps from Apps, removes proxy/TLS configuration options, and updates respond() to return native Response objects.
Affects one of your integrations? We take over the migration, at a fixed priceMultiple Node Slack SDK package updates: All Node Slack SDK packages now require Node.js 20+; web-api updated to v8, webhook updated to v8, socket-mode updated to v3, all migrating from axios to Fetch API.
Multiple Node Slack SDK package updates: Major version updates across Node SDK packages requiring Node.js 20+, with significant breaking changes in socket-mode, web-api, and webhook packages related to HTTP transport.
Slack desktop client notifications now extract text from blocks first before falling back to top-level text field; mobile notifications unchanged.
Desktop notifications changed to prioritize text from blocks over top-level text field, mobile notifications continue using message.text only.
New app_context_changed event and app_context field in message.im and app_home_opened events allow agent apps to receive context about user's current viewing location (channel, DM, thread, canvas, list).
New app_context_changed event and app_context field in message.im and app_home_opened events to provide context about user's active view.
New agent_view feature deprecates assistant_view for agent conversations, changing DM detection to use app_home_opened event instead of assistant_thread_started and making thread_ts optional for suggested prompts.
New agent_view messaging experience replacing assistant_view, with changes to app_home_opened events, suggested prompts location, and conversation continuation logic.
Slack CLI v4.4.0: Slack CLI v4.4.0 adds support for features.agent_view app manifest property to enable the new Agent messaging experience.
Python Slack SDK v3.43.0: Added public ts property to ChatStream, made thread_ts optional for setSuggestedPrompts method.
Container block is now available for Block Kit use.
New Slackbot MCP Client allowing developers to connect MCP servers with multiple authentication methods for tool discovery and invocation.
Slack CLI v4.3.0: Added --app flag to create command, external-auth add-secret for all apps, and mcp_server manifest field support.
New version adds --app flag for scaffolding, external-auth command availability, and MCP server manifest field support.
Breaking change: system notifications now sent from USLACK instead of Slackbot, requires apps to update logic filtering by Slackbot user ID or username.
Breaking change: System notifications migrated from Slackbot (U025AQVCU) to new Slack system user (USLACK); apps filtering by Slackbot user ID or username must update integration logic.
Data visualization block is now available for Block Kit use.
Java Slack SDK v1.49.0: Added authorship arguments to assistant.threads.setStatus and chat.startStream methods; added highlight_type support to file upload methods.
Slack CLI v4.2.0: Added unauthenticated request support to slack api command, disabled upgrade notifications for manifest commands, and improved Y/N prompt displays.
Slack CLI v4.2.0: Added unauthenticated request support to slack api command, improved Y/N prompts, disabled upgrade notifications for manifest commands.
Added unauthenticated request support to slack api command, improved UI formatting, disabled upgrade notifications for manifest commands.
Data table block is now available for Block Kit use.
Slack CLI v4.1.0: Added slack api command to call any API method directly, improved accessibility support, added env init command, added MCP server manifest field support, added optional OAuth scopes support, improved icon handling and auto-detection.
Slack CLI v4.1.0: Added slack api method command, screen reader accessibility support, env init command, mcp_server and optional OAuth scopes manifest support.
Slack CLI v4.1.0 adds slack api command to call any API method directly, improved environment variable management, and support for optional OAuth scopes.
New CLI features including slack api command, screen reader support, env management improvements, and MCP Server configuration support.
CLI adds slack api command for direct API method calls, screen reader support, env init command, MCP server manifest support, and optional OAuth scopes.
Python Slack SDK v3.42.0: Added authorship arguments to assistant and chat methods, highlight_type support for file uploads, new Block Kit blocks support.
Five new tools added to Slack MCP server: add reactions, create conversations, list channel members, list emoji, and read files.
Three new Block Kit blocks (alert, card, carousel) added and streaming API methods updated to support streaming blocks.
Added alert, card, and carousel blocks to Block Kit with streaming API support for blocks in chat methods.
Slack CLI v4.0.0 and v4.0.1: Major CLI update with agent development focus including new AI Agent templates, environment variable management from .env files, file watching with live reloading, local manifest management, and improved Python project support.
Slack CLI v4.0.0 and v4.0.1: Major release with agent development focus: new AI agent templates (Starter and IT Support agents), environment variable management (.env files loaded before hooks), file watch with live reload, improved Python project setup with virtual environments, and refreshed prompt UI.
Slack CLI v4.0.0 and v4.0.1: Major CLI version with agent development templates, environment variable management, file watching with live reload, and improved Python project handling.
Slack CLI v4.0.0 and v4.0.1: Slack CLI v4.0.0 includes new AI Agent templates with IT support agent, improved environment variable management with .env file loading before hooks, and better template categorization for slack create command.
Major update focused on AI agent development with scaffold templates, file watching with live reload, environment variable management, and agent framework support including Claude, OpenAI, and Pydantic AI.
PKCE (Proof Key for Code Exchange) authentication flow is now generally available for enhanced security.
Slack CLI v3.15.0: CLI improvements including local manifest.json support by default, app manifest overwrite warnings, and manifest source configuration.
Slack CLI v3.15.0: Normalized project directory names to kebab-case, improved app name prompt with placeholder text, switched to local manifest.json by default, and updated slack app link command.
Updates include kebab-case project directory normalization, local manifest.json default for Bolt projects, manifest source detection, and app manifest overwrite warnings.
Optional scopes feature now available allowing developers to request bot_optional and user_optional scopes.
Rich text and markdown blocks now support syntax-highlighted code blocks, tables, task lists, dividers, and variable-sized headers.
Slack CLI v3.14.0: CLI updates include custom app name prompts, Python virtual environment (.venv) support, automatic Python venv activation, and --subdir flag for monorepo-style templates.
assistant.threads.setStatus API method now accepts chat:write scope in addition to assistant:write, allowing channel-based apps to use AI loading states without requesting assistant:write scope.
Bug fixes and improvements to Slack CLI tooling.
Slack CLI v3.13.0: Slack CLI update with improved agent app template selection, template listing without immediate selection, and auto-login prompts for commands requiring credentials.
Slack CLI v3.13.0: Highlighted agentic apps in slack create agent command, added --list flag to show templates without immediate selection, and improved login prompts.
Updates and improvements to Slack CLI.
New Slack MCP server and Real-time Search API released, enabling AI-powered search and tool integration capabilities.
New Block Kit components (task_card, url source, plan blocks) and task_display_mode parameter for text-streaming API methods enable display of app actions.
New plan and task card blocks allow apps to display agent thinking steps and task progress to users.
Slack CLI v3.12.0: CLI updates including pyproject.toml support, file watching with live reload for Bolt projects, and manifest change detection.
New Delayed Events feature allows replaying past events that apps may have missed during outages.
Slack CLI v3.11.0: Slack CLI v3.11.0 maintenance release with behind-the-scenes updates.
Classic apps deprecation timeline has been paused.
Slack CLI v3.10.0: New slack app unlink command and support for read-only app collaborators for deployed Deno apps.
Maintenance release with deno-slack-hooks v1.5.0 update adding support for bundling deno-slack-sdk projects with deno bundle command.
Maintenance release with behind-the-scenes updates.
OAuth page redesigned with improved user experience.
Work Objects now generally available with unfurl and flexpane components, new entity_details_requested event, and entity.presentDetails API method.
New Work Objects feature enabling structured data management and collaboration within Slack.
Slack CLI v3.9.0: Work Objects support in manifest with entity_types gathering and improved installation script to avoid blocking on version update prompts.
New features and improvements to CLI tooling.
Updates to Slack API Terms of Service.
Bug fix release for CLI.
New chat streaming features and block support for AI-generated responses.
New features released specifically designed for Slack apps that send AI responses, including streaming text and other AI-related capabilities.
Slack CLI v3.8.0: Slack CLI v3.8.0 adds sample listing capability, deprecates --branch and --template flags, and documents hooks.json specification.
New features and improvements to developer tools.
Slack CLI v3.7.0: Slack CLI v3.7.0 improves macOS/Linux installation path handling and adds app manifest search field parsing.
New features and improvements to developer tools.
New Lists API released for managing lists in Slack workspaces.
New Lists API for creating and managing list data structures in Slack.
Slack CLI v3.6.1: Slack CLI v3.6.1 removes deno runtime from installer and recommends separate installation.
Documentation migration to new docs.slack.dev site.
The allow_message_deletion field is being deprecated.
New table block available for Block Kit use.
Slack CLI v3.5.2: Slack CLI v3.5.2 announces removal of deno from installation script starting September 1, 2025, and improves error messaging.
Classic apps deprecation timeline has been extended.
New featured workflows API available for discovering and managing featured workflows in the Slack platform.
New API for creating and managing featured workflow templates in Slack.
Slack CLI v3.5.1: Slack CLI v3.5.1 adds user feedback prompts during installation errors.
Slack Marketplace apps now required to have minimum installations on active workspaces to be eligible for Marketplace submission.
Timeline for retiring api.slack.com has been adjusted.
Clarification provided on rate limit changes for non-Marketplace apps.
Slack API Terms of Service have been updated; developers should review changes to ensure compliance.
Rate limits for non-Marketplace apps have been updated, requiring apps to adjust their API call patterns accordingly.
Classic apps deprecation timeline has been adjusted multiple times; currently paused as of December 2025.
Slack CLI released as open source software.
api.slack.com is being retired; developers must migrate to docs.slack.dev for API documentation and references.
Timeline for files.upload method deprecation has been extended; developers should migrate to new file upload methods.
Slack platform API and tools documentation is now available in beta on docs.slack.dev, providing early access to updated content.
The Slack CLI deno command is being removed from the platform.
Major Slack CLI version 3.0.0 released with significant features and improvements.
New markdown block added to Block Kit.
New markdown-specific block added to Block Kit for better markdown content rendering.
New Data Access API released for secure access to Slack data through search interface.
New Data Access API released for accessing Slack workspace data.
Slack App Developer Policy has been updated.
API documentation is migrating from api.slack.com to docs.slack.dev.
New Agents & AI Apps feature released enabling development of AI-powered agent applications.
Breaking change: Legacy custom bots and classic apps support is being discontinued affecting older app implementations.
Custom workflow steps feature now available to all Slack apps providing workflow extensibility.
Breaking deprecation: files.upload method is deprecated and will be replaced by sequenced Web API methods.
New creation of classic apps and legacy custom integration bots has been discontinued.
New file upload functionality added to Block Kit enabling file uploads in messages and modals.
New capability to securely render internal images in modals and messages with proper authorization.
Rich text formatting capabilities added to Block Kit surfaces for more expressive messaging.
We watch Slack because we run integrations on it. If one of yours depends on Slack, we can take it over: build it properly, operate it, and fix it when Slack changes, before your data is affected. Fixed-price scoping quote within 48 hours.