I had lunch this week with the managing partner and eDiscovery practice head of a law firm in Lake Oswego, Oregon. He asked about what kind of product we built, and his first reaction was:

"Ah, you guys have figured out Slack, huh!"

This isn't a phrase you would hear when discussing eDiscovery of emails or PDF documents. As my lunch partner and I knew, Slack data is uniquely challenging to access and review for legal discovery, in comparison to the data you can export from Google Vault or Microsoft Purview. How is this the case?

Slack has become a home for teams. It’s where they chat, make decisions, and disagree throughout the workday. That means when a dispute, investigation, or audit touches Slack comms, it requires a sprawling, compliant search. 

When a Slack investigation starts, most teams hit the same wall: they try exporting Slack conversations, but end up with an unreadable mass of JSON files. It’s practically unworkable and can become costly. One white paper found that merely uploading a 200-gigabyte (GB) Slack export file to Relativity (a popular eDiscovery platform) can cost you $10 per gigabyte, per month in hosting fees alone.

This practical Slack eDiscovery guide will help you navigate the export & search processes, and is designed for:

• IT / Security teams who own Slack in their org.
• In-house Legal / HR / Compliance teams. 
• Law firms and eDiscovery providers handling Slack for clients.

Real-World Slack Matters (Patterns We See)

Slack eDiscovery shows up more often than you might think, because it’s a hub for candid and quick work communication. That means when something goes wrong (or simply needs to be verified), Slack is often part of the record.

Slack searches come up in cases such as:

• Employment / Slack harassment investigations in private channels and DMs.
• Leaks or pre-IPO chatter in “informal” project channels.
• Regulators asking for internal communications around an outage or launch.
• Slack DSAR requests that explicitly mention Slack channels or DMs.

Most Slack investigations follow the same pattern, and Slack evidence is often the most critical, relevant record of what actually happened. However, extracting it in a way that’s complete, defensible, and reviewable is harder than most teams expect.

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Is Slack eDiscovery Possible Out Of The Box?

For anything beyond a very simple matter, you'll probably need a third party tool in addition to Slack's own functionality.

How much eDiscovery you can do with Slack depends heavily on your plan:

What Most Teams Get Wrong the First Time

Slack eDiscovery might seem straightforward enough – just request an export, receive your files, and breeze through the data. 

But most teams miss the mark, because they:

1. Treat Slack like email (missing threads, reactions, & edits)

Slack isn’t linear. Key context lives in threaded replies, emoji reactions, message edits, and file shares, None of which map cleanly without additional tools. 

Better way: to use a tool that reconstructs conversations as Slack actually displayed them.

2. Assume legal can “just look at the JSON”

A raw export is technically complete. However, files arrive in a huge, unreadable pile of JSON files, nested in a web of folders, and it’s nearly impossible to find and filter for a specific data set. 

The better way: convert JSON into a review-ready format before legal (or anyone) touches it.

3. Export everything and sink review in noise

The “export everything” approach slows reviews to a crawl, and trawling JSON files at that volume takes hours of expensive manual effort.

Better way: Collect narrowly and defensibly around custodians, dates, and channels.

4. Run ad-hoc admin searches (without approvals or logs)

Dumping Slack export data en masse opens you up to risk. You need to stay compliant, auditable, ensure security, and keep a record of access – all while handling people’s sensitive information. 

Better way: Use a permissioned, logged workflow with clear authorization and audit trails.

4. Only searching text, not also attachments and links

Slack conversations frequently include file attachments, document links, and integrations with other business tools. These elements often contain the most legally relevant information, yet they can be easily overlooked in basic export processes.

While they might seem trivial, emoji reactions in Slack can carry significant legal weight. A thumbs-up reaction to a message about a business decision could indicate approval or agreement. Multiple team members reacting with specific emojis might demonstrate consensus or concern about a particular issue. The legal significance of emoji reactions has gained recognition in court proceedings, with some courts acknowledging emoji as legally significant indicators of agreement or intent. Preserving reaction data must be part of a comprehensive Slack legal hold process.

One-Week Comparison: Email vs Slack

If you want a quick sense of why Slack eDiscovery is different (and more valuable) than email reviews, run this simple exercise:

1. Pick one team and one week for a test.
2. Count how many emails they sent internally. Count how many Slack messages they send in the same period.
3. Take note of the amount of:

• Slack messages under 20 words.
• Threads with >10 replies.
• Messages with attachments/links.

Most organizations find the contrast striking. Usually, Slack volume is dramatically higher, messages are shorter, and context lives in replies, reactions, and linked files – not just in the message body itself. A single thread can contain more back-and-forth than a week of email.

For discovery, this often results in an overwhelming volume of data to review and rapidly rising costs.

Slack-Specific eDiscovery Problems

Without the right tools and processes in place, Slack eDiscovery is almost impossible. 

Here are common problematic scenarios teams run into:

Key decisions buried deep in a thread

A product team is debating rolling out a key feature in a channel. The actual decision happens in reply #14 of a fast-moving thread, not in the top-level message. When the export splits everything into flat JSON objects, that decision point becomes buried, unless the thread is reconstructed.

“Private” multi-person DMs that become central to a dispute

Three managers hash out how to handle a performance issue in a group DM, assuming their conversation is private. Months later, that conversation is the core of an employment claim. Without proper handling, multi-party DMs get scattered across files and lose their sequence.

Emoji, edits, and deletes change how a message reads later

A thumbs-up may signal approval. A later edit may soften or escalate the tone. A delete may become relevant if someone claims the message never existed. Slack tracks all of this, but JSON exports don’t surface the nuance unless you know where (and how) to look.

Plans, History, Exports, Discovery API (At a Glance)

Your Slack plan tier determines what data you can collect and how far back your history goes. Here’s what that looks like:

Quick “Plan Fit” Questions

A few fast checks help determine whether your current Slack plan can properly support the matters you’re handling:

If you deal with more than 3 matters/year involving Slack and you often need more than 90 days of history → Free is a risk.

You’ll spend more time chasing missing messages than reviewing evidence.

If regulators often ask about comms → push for Business+ or Slack Enterprise Grid

You’ll need reliable Slack retention, complete history, and export options that hold up under scrutiny.

If you already have eDiscovery vendors → match plan to their needs, not just IT’s

Your vendor’s tooling and workflows determine what’s defensible and efficient – choose the plan that aligns with that reality.

What Needs to Survive Into Review

Slack communications are a key part of your Slack ESI (electronically stored information), and they’re only truly valuable, helpful evidence if the context remains intact. When you convert exports into a review-ready format, make sure these elements make it through:

• Threads and reply chains.
• Attachments and linked docs.
• Reactions and edit history.
• Who said what, when, and in which channel.

How to Preserve Context Without Drowning in Data

The goal with effective eDiscovery is not to sweep up everything in an investigation – it’s to collect the right material without stripping away context.

A few concrete practices help keep Slack evidence usable and defensible:

Review by thread, not isolated messages

Slack conversations unfold vertically. Rebuilding threads preserves the flow of decisions, disagreements, and clarifications that would otherwise disappear in a flat export.

Keep attachments and reactions bound to the thread

An approval reaction, a shared doc, or a linked file often completes the record.

Use tools that show chronological timelines (not flat CSVs)

A timeline view shows how messages, edits, and reactions played out in real time – critical when assessing intent or sequence.

Examples from the field: Say a team supplied opposing counsel with a text-only export stripped of threads, reactions, and file references. The data technically included every message, but none of the context. Opposing counsel challenged completeness and argued that message order was ambiguous. The producing team had to execute a costly, time-consuming manual review under pressure to recover.

Seven Steps You Repeat Every Time

A smooth, defensible Slack review workflow can be simple, especially when you approach it methodically.  

Here are step-by-step instructions to follow whenever you need to do a Slack review: 

1. Scope

Start by defining exactly what you’re collecting and why. Identify custodians, key channels, and the date window tied to the issue. 

Just as important: write down what you’re not collecting, such as private channels you ruled out and date ranges that don’t apply. Negative scope helps keep your project contained and defensible. 

2. Collect

Decide whether you’re pulling a native export or using the Slack Discovery API. Either way, record who is approved for the data collection, and when they accessed the data. 

3. Normalize

Raw JSON ≠ review material. Convert your export into threaded, readable conversations with IDs, timestamps, reactions, edit flags, attachments, and channel metadata intact.

4. Search & Cull

Run targeted searches to reduce noise. For example, by targeted keywords, relevant channels, and a narrow date window. As you go, keep a simple “search log,” tracking queries and why you ran them. That way, if someone later asks why a certain set was included or excluded, you can answer cleanly.

5. Review & Tag

Review data and tag at thread-level where possible, to cut review time, reduce rework, and ensure secure access.

Keep tags simple and consistent: responsive, non-responsive, privileged, follow-up.

6. Produce & Handoff

Deliver only what’s minimally required (with clear naming), not an entire workspace dump. Tailor the output to the destination – clean things up for opposing counsel, or load structured files into tools like Relatively/Everlaw.

7. Retrospective

After the matter closes, take 10–15 minutes to review what worked, what didn’t, and what should change next time, to improve processes (and ensure they hold up under pressure). 

A Simple Hold/Retention Model You Can Explain Out Loud

You don’t need a complex retention strategy to manage Slack comms defensibly. Here are simple hold/retention guidelines to follow:

Level 1: everyday channels (standard retention)

Most team chatter lives in these channels. Apply your normal workspace retention policy here (such as 90 days) – these channels aren’t tied to known issues.

Level 2: HR/compliance channels (longer retention)

Channels where sensitive or escalated conversations happen – HR operations, investigations, compliance reviews – need more runway. Extend retention so these records are available if questions arise months later.

Level 3: people/channels on legal hold (no deletion)

When a matter triggers Slack legal holds, stop deletion for relevant custodians and channels immediately. This ensures you can reconstruct conversations without gaps.

Common Misconfigurations We See

Certain habits can make Slack eDiscovery even more challenging. These are patterns that show up again and again (which you want to avoid):

Everything set to “keep forever” because no one wants to decide

It might feel safer, but keeping everything forever balloons storage, expands every review set, and exposes years of irrelevant or sensitive content.

HR or leadership channels on very short retention

HR/leadership channels are often the places where sensitive decisions, complaints, and escalations occur. Short retention here means missing context when issues resurface.

Legal holds applied to email – but Slack left untouched

Teams assume the email hold covers “communications,” but Slack continues deleting messages in the background. By the time someone notices, gaps in the record are permanent and hard to explain.

Avoid “Just Export Everything”

A full Slack data export might sound clean and neutral, but it usually does more harm than good. Before you pull an entire archive, run a basic Slack early case assessment of volume vs. sensitivity. High-volume channels full of daily chatter are rarely what you’re looking for. Instead, focus on smaller pockets of sensitive communications, such as HR escalations, project threads, or relevant private groups.

It’s often worth doing a pre-cull in a purpose-built Slack JSON viewer before handing anything to your main review platform. Threaded search, channel filtering, and tight date windows can reduce the dataset dramatically, while highlighting the info you actually need. 

When DIY JSON Scripts Stop Being Defensible

If you’re doing an internal spot-check, DIY JSON script trawling might be suitable – especially if you’re trying to answer a narrow question for an internal team. But once a case is larger, you’re dealing with regular queries, or a regulator or court is involved, the standards change. You need consistent parsing, clear logs, and a repeatable workflow that can stand up to external challenges.

A small but common example: let’s say an engineer writes a manual script for a Slack export that sorts messages by timestamp field, without accounting for Slack’s editing features. The result merges edited messages at the wrong place in the timeline, and excludes messages that the sender had deleted. The final product might look complete, but it doesn’t reveal the entire picture. 

Solving the Slack Export Problem

Instead of drowning in a mountain of raw JSON files, you can make your Slack data readable and searchable by using a user-friendly Slack export viewer like ViewExport.

Here’s how Slack eDiscovery tools work, and how they fill the gaps in your tech stack & processes:

1. Upload your Slack ZIP file. Instead of flat JSONs, instantly see threaded, searchable conversations.
2. Filter by user, channel, or keyword to isolate only the parts of the workspace that matter.
3. When it’s time to hand off results, export focused data for CSV or tools like Relativity/Everlaw.
4. Throughout the process, log who searched what, when, and what they exported, to leave a clean Slack audit trail and a defensible Slack chain of custody.

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In short: Slack export viewers are purpose-built for eDiscovery, and turn your JSON archives into readable, review-ready evidence with defensible workflows

Two Concrete Use Cases

When might using one of the top eDiscovery tools be right for you?

If you’re an in-house team handling ad-hoc HR cases, your investigations can hinge on a few private channels and DMs. Here’s how it works: IT pulls a Slack export, quickly uploads it to ViewExport, and immediately sees conversations in threaded form. From there, they filter, isolate immediately, see the conversations in threaded form, and immediately start a targeted review.

These tools are also right for you if you’re a law firm or eDiscovery provider – a business consistently supporting clients. Instead of writing new parsing scripts or coming up with unique workflows each time, you can run every Slack data archive through ViewExport. Intake becomes predictable and useful, and manual work is replaced with a standardized Slack workflow across all clients.

Make Slack eDiscovery Boring and Repeatable

Slack data exports are messy by design. Your eDiscovery process shouldn’t inherit that chaos. To keep things simple, when a case comes up, use the same seven-step process every time, and aim to be able to explain things in under two minutes to a judge, regulator, or DPO.

Have a Slack export you can’t use yet? Drop it into ViewExport, search and filter it down to what matters, and send the result to opposing counsel or your eDiscovery platform with a clear audit trail. Try it with a test export, or book a walkthrough with your IT and legal team together.