mailfloss vs TheirStack: Data Enrichment Tool Comparison
Compare mailfloss and TheirStack side by side. See pricing, features, and integrations to choose the right data enrichment tool for your needs.
mailfloss and TheirStack both serve B2B lead data and contact enrichment needs but differ sharply in focus and price. mailfloss is an email verification service starting at $29/mo that cleans lists daily, while TheirStack is a job posting and technographics database with a free entry tier at $0/mo. The right pick depends on budget and required capabilities.
Key takeaways
- mailfloss pricing starts at $29/mo for the Lite plan with 10,000 credits per month, rising to $209/mo for Pro with 125,000 credits per month.
- TheirStack offers a Free plan with 50 company credits and 200 API credits per month, plus an API, Webhooks and MCP plan at $49/mo for 1,500 API credits per month.
- mailfloss lists 10 features including cleans your list daily, custom keep and remove rules, and real-time API, while TheirStack lists job search, company search, and an MCP server.
- mailfloss integrates with 29 tools including Mailchimp, Klaviyo, HubSpot, and ActiveCampaign, while TheirStack integrates with Clay, LinkedIn Audiences, Make, and N8N.
- Both mailfloss and TheirStack share webhooks and Zapier as common capabilities and integrations.
Reviewed and updated September 4, 2026
mailfloss vs TheirStack: Data Enrichment Tool Comparison
If you are comparing B2B lead data and contact enrichment tools, mailfloss and TheirStack will likely both appear on your radar. They share some surface-level similarities, but the details reveal important differences in pricing, capability, and target audience.
The Quick Answer
By each vendor's own wording, mailfloss lists cleans your list daily and removes addresses that decay over time, while TheirStack lists job search and company search. A capability both offer can appear under different names, so read both feature lists below.
TheirStack offers a lower entry point at $0/mo compared to mailfloss at $29/mo.
If your priority is finding accurate contact data for target accounts, both tools target it. The right choice depends on your budget, team size, and the specific capabilities you need most.
Understanding the Core Difference
mailfloss is mailfloss is an email verification service that connects to your email marketing platform and cleans the list daily on autopilot, removing bad addresses, fixing typos and blocking bot and spam signups in real time. Subscriptions are sized by credits per month; prepaid credits cover one-time list uploads.
TheirStack is Job posting and technographics database for sales teams. Finds companies by the technologies they use and the roles they are hiring for, and enriches a company list with technographics and buying intent.
Both platforms offer webhooks. Where they diverge is in their approach to pricing tiers and advanced capabilities.
Pricing Comparison
Lite
Free
mailfloss Pricing (as of September 2026)
| Plan | Price | Emails |
|---|---|---|
| Lite | $29/mo | 10,000 credits/month |
| Business | $59/mo | 25,000 credits/month |
| Pro | $209/mo | 125,000 credits/month |
| Prepaid credits | Usage-based | - |
Source: mailfloss Pricing
TheirStack Pricing (as of September 2026)
| Plan | Price | Contacts |
|---|---|---|
| Free | Free | 50 company credits and 200 API credits per month |
| App | Usage-based | Company credit packs from 1,000 to 200,000 credits |
| API, Webhooks & MCP | $49/mo | 1,500 API credits per month |
| Datasets | Contact Sales | Jobs, Technographics and Buying intents datasets |
Source: TheirStack Pricing
Pricing Analysis
TheirStack offers the lower entry point ($0/mo vs $29/mo). Teams watching their budget will appreciate the savings, especially when starting out.
TheirStack includes a free tier, which is helpful for evaluating the platform without upfront cost.
Features Breakdown
- Cleans your list daily
- Removes addresses that decay over time
- Custom keep and remove rules
- Zapier integration
- Real-time API
- Automatically fixes typos
- and 3 more listed below
- Webhooks
- Job search
- Company search
- Company lookup
- Enrichment
- Exports
- Email alerts
- and 1 more listed below
mailfloss Key Features
- Cleans your list daily
- Removes addresses that decay over time
- Custom keep and remove rules
- Zapier integration
- Real-time API
- Webhooks
- Automatically fixes typos
- Prevents bounces in real-time
- Auto-tags subscribers after verification
- Single sign-on
TheirStack Key Features
- Job search
- Company search
- Company lookup
- Enrichment
- Exports
- Email alerts
- Webhooks
- MCP server
Shared Capabilities
Both mailfloss and TheirStack include:
- Webhooks
The two lists below are a diff of each vendor's own feature list by exact wording, so a capability both tools offer can appear on either side under a different name.
Listed only by mailfloss
- Cleans your list daily
- Removes addresses that decay over time
- Custom keep and remove rules
- Zapier integration
- Real-time API
- Automatically fixes typos
- Prevents bounces in real-time
- Auto-tags subscribers after verification
- Single sign-on
Listed only by TheirStack
- Job search
- Company search
- Company lookup
- Enrichment
- Exports
- Email alerts
- MCP server
Integration Ecosystem
mailfloss Integrations
mailfloss connects with: Mailchimp, Klaviyo, HubSpot, ActiveCampaign, Kit, beehiiv, GoHighLevel, Braze, AWeber, Drip, MailerLite, Constant Contact, Brevo, Campaign Monitor, GetResponse, Ontraport, iContact, Sendlane, Moosend, Keap, Intercom, Customer.io, Iterable, Ghost, Emma, SendPulse, Benchmark, Mautic, Zapier.
TheirStack Integrations
TheirStack connects with: Clay, LinkedIn Audiences, Make, N8N, Zapier.
Shared Integrations
Both tools integrate with: Zapier.
Integrations listed only by mailfloss: Mailchimp, Klaviyo, HubSpot, ActiveCampaign, Kit, beehiiv, GoHighLevel, Braze, AWeber, Drip, MailerLite, Constant Contact, Brevo, Campaign Monitor, GetResponse, Ontraport, iContact, Sendlane, Moosend, Keap, Intercom, Customer.io, Iterable, Ghost, Emma, SendPulse, Benchmark, Mautic.
Integrations listed only by TheirStack: Clay, LinkedIn Audiences, Make, N8N.
Use Case Recommendations
Best Fit for mailfloss
- Budget-conscious teams looking for an affordable data enrichment tool
- Teams that need a wide feature set (10 capabilities listed)
- Organizations with complex tech stacks needing broad integration support (29 integrations)
- Enterprise buyers who prefer custom pricing and dedicated support
Best Fit for TheirStack
- Budget-conscious teams looking for an affordable data enrichment tool
- Teams that want to start free and scale up as needs grow
- Enterprise buyers who prefer custom pricing and dedicated support
Feature Comparison Summary
| Feature | mailfloss | TheirStack |
|---|---|---|
| Starting Price | $29/mo | Free |
| Top Tier Price | Usage-based | Contact Sales |
| Total Features Listed | 10 | 8 |
| Integrations | 29 | 5 |
| Founded | N/A | 2021 |
Getting Started Checklist
- Define your B2B lead data and contact enrichment requirements and monthly budget
- Estimate your expected data credits or contact lookups to find the right tier
- List the integrations your team currently relies on
- Sign up for free trials or demos of both platforms
- Run a small test with each tool before making a commitment
- Evaluate the onboarding experience and support quality
Final Thoughts
mailfloss and TheirStack both serve the B2B lead data and contact enrichment market. TheirStack offers a more accessible entry point, while mailfloss starts at $29/mo. Your decision should weigh pricing against the specific features that matter most for your workflow.
Start with a trial of each to see which platform fits your team's daily process. The best tool is the one your team actually uses consistently.
Pricing and features verified as of September 2026. Visit mailfloss and TheirStack for current information.
Frequently asked questions.
Frequently asked questions- What is the main difference between mailfloss and TheirStack?
- mailfloss is an email verification service that connects to your email marketing platform and cleans your list daily on autopilot, while TheirStack is a job posting and technographics database that finds companies by technologies used and roles being hired for. They target different parts of the data enrichment workflow.
- Which tool is cheaper, mailfloss or TheirStack?
- TheirStack has the lower entry point at $0/mo with its Free plan, compared to mailfloss which starts at $29/mo for its Lite plan. TheirStack's free tier includes 50 company credits and 200 API credits per month, making it useful for evaluation without upfront cost.
- Do mailfloss and TheirStack integrate with the same tools?
- They share one common integration, Zapier. Beyond that, mailfloss connects with 29 tools including Mailchimp, Klaviyo, HubSpot, and ActiveCampaign, while TheirStack connects with only Clay, LinkedIn Audiences, Make, and N8N in addition to Zapier.
- Which tool has more features, mailfloss or TheirStack?
- mailfloss lists 10 features on its own page, including cleans your list daily, custom keep and remove rules, real-time API, and single sign-on. TheirStack lists 8 features, including job search, company search, enrichment, exports, and an MCP server.
- Who should choose mailfloss over TheirStack?
- Budget-conscious teams looking for an affordable data enrichment tool, teams needing a wide feature set of 10 capabilities, organizations with complex tech stacks needing broad integration support across 29 integrations, and enterprise buyers who prefer custom pricing and dedicated support are best suited to mailfloss.
About the author.
Tim Carden is CMO / CTO at RevenueFlow, which builds and operates outbound revenue engines for B2B companies. Studied at McGill University.
Tim Carden · CMO / CTO
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