Migrate from Slack to Trello

Each Slack public channel maps to a Trello board. The Slack channel name becomes the board title, the channel description (purpose field) becomes the board description, and the Slack channel topic becomes the board welcome card. We preserve the Slack channel ID in a custom field on the board for audit traceability. Channel creation date maps to the board's creation timestamp. Public channels are fully exportable on Slack Free and Pro tiers via the admin export tool.

Private Slack channels require Business+ for native export or im:read/groups:read API scopes for programmatic extraction. We map them to Trello private boards, preserving channel name, description, and membership as board members. The channel membership list does not transfer as a Trello board membership automatically; we extract it as a member list CSV for manual invitation post-migration since Trello board invite is an admin action.

Slack message threads map to Trello cards with the channel's topic as the card title and the parent message as the card description. Each thread reply becomes a checklist item on that card, preserving the author display name, timestamp, and message text. This flattens the conversational tree structure into a linear checklist format that Trello's model supports. We truncate checklist items exceeding Trello's 500-character limit per item and flag truncation in the migration report. Thread reactions migrate as a note at the bottom of the checklist item listing reaction emoji and reactors.

Slack channel topic (pinned by the channel admin) and the pinned message list migrate as the initial card description on a designated welcome card within each board. We preserve the original pinned message author, timestamp, and text. Re-pinning inside Trello (if needed) is a manual step since Trello does not have a native pin equivalent; we document the pinned content as a bulleted list in the card description with links to source URLs.

DMs and group DMs have no native Trello equivalent. We extract DM content via the Slack conversations.history API (Business+ required or approved Enterprise export) and generate a structured card per DM thread in a designated archive board. The card contains the conversation as a chronological list of message entries (author, timestamp, text) in the card description. This is a preservation format, not a functional Trello workflow — the customer should treat it as a reference archive rather than active work. We flag this limitation explicitly in the migration scope.

Slack workspace members map to Trello workspace members by email address match. We extract display name, email (Business+ required), timezone, and custom status from Slack. Trello's permission model (Board Member, Workspace Member, Observer) does not map directly from Slack's Owner/Admin/Member/Guest roles, so we export the role data as a CSV attached to the member invitation spreadsheet for the customer's admin to assign Trello roles manually post-migration.

Slack file metadata (name, URL, uploader, timestamp, MIME type, size) migrates as Trello card attachments. We download accessible file blobs during export and upload them as Trello card attachments where the destination board has available storage under its Power-Up limits. Files that return 404 (deleted or purged from Slack storage) are logged as broken link entries in the migration report. Files exceeding Trello's 250MB per-file limit or Power-Up storage quota are preserved as external URL links on the card instead of uploaded blobs.

Slack emoji reactions on messages (name:count format, e.g., thumbsup:5) are preserved as inline notation in the migrated card description or checklist item. Custom emoji exports as a name-to-image mapping JSON. We do not re-upload custom emoji to Trello since Trello does not support workspace-level custom emoji — we attach the emoji image file as a card attachment instead and note the original emoji name in the description. This is a best-effort preservation, not a native equivalent.

Slack User Groups (subteams) export with membership lists. We map them to Trello board labels with the group name as the label name and a descriptive color. Workspace-level group membership does not map to Trello natively, so we export the group membership as a CSV (member email, group name, role) for the customer's admin to use when assigning Trello board members or labeling cards by team.

Slack Business+ channel audit report (CSV with channel name, creation date, member count, channel purpose) migrates as metadata in each corresponding Trello board's description. This preserves the administrative context (who created the board, when, and for what purpose) that Trello boards do not store natively.

Slack Saved Items (starred messages) are user-specific and stored in Slack's client-side UI state. They are not included in workspace exports or accessible via the Slack API for cross-user migration. We do not migrate Saved Items. We flag this as a gap in the migration report and recommend the customer communicate to users that they should manually export their Saved Items before the migration window. We provide a script reference for users to export their own saved items via the Slack client export feature.

Installed Slack apps, OAuth tokens, bot tokens, incoming/outgoing webhooks, slash commands, and Slack Connect external channel configurations do not transfer to Trello. We produce a written inventory of every installed Slack app with its OAuth scopes, connected workspaces, and business-critical flag during scoping. The customer's admin reinstalls and reauthorizes each app inside Trello or an equivalent automation tool post-migration. We flag which integrations (e.g., Zendesk, Jira, GitHub) have native Trello Power-Ups and provide the setup links.