Seamless.AI vs TheirStack: Data Enrichment Tool Comparison
Compare Seamless.AI and TheirStack side by side. See pricing, features, and integrations to choose the right data enrichment tool for your needs.
Seamless.AI and TheirStack both offer free plans starting at $0 per month, but they serve different needs. Seamless.AI is a real-time B2B contact search and enrichment platform with 10 listed features and 7 integrations, while TheirStack is a job posting and technographics database with 8 features and 5 integrations. The right choice depends on budget, team size, and required capabilities.
Key takeaways
- Both Seamless.AI and TheirStack offer free plans starting at $0 per month.
- Seamless.AI lists 10 features total compared to TheirStack's 8 listed features.
- Seamless.AI integrates with 7 platforms including Salesforce, HubSpot, and Pipedrive, while TheirStack integrates with 5 platforms including Clay and LinkedIn Audiences.
- TheirStack offers 4 pricing tiers compared to Seamless.AI's 3 tiers, including an API, Webhooks and MCP plan priced at $49 per month for 1,500 API credits.
- Seamless.AI was founded in 2015 while TheirStack was founded in 2021.
- Zapier is the only integration shared by both Seamless.AI and TheirStack.
Reviewed and updated September 4, 2026
Seamless.AI vs TheirStack: Data Enrichment Tool Comparison
Sales teams evaluating B2B lead data and contact enrichment tools often narrow their shortlist to Seamless.AI and TheirStack. Both target the same job, but they cater to different workflows and budgets. This comparison covers pricing, features, and integrations so you can pick the right fit.
The Quick Answer
By each vendor's own wording, Seamless.AI lists real-time b2b contact search engine and email and cell phone lookups, while TheirStack lists job search and company search. A capability both offer can appear under different names, so read both feature lists below.
Both start at the same price point ($0/mo), so the decision comes down to features and workflow fit.
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
Seamless.AI is AI-powered sales lead platform with real-time contact search engine, pitch intelligence, and data enrichment for B2B prospecting.
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.
The two platforms take different approaches to solving the same core challenge.
Pricing Comparison
Seamless.AI Pricing (as of September 2026)
| Plan | Price | Contacts |
|---|---|---|
| Free | Free | 50 Credits |
| Pro | Contact Sales | Annual Credit Packages |
| Enterprise | Contact Sales | Custom Packages |
Source: Seamless.AI 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
Both platforms start at the same $0/mo price point. The decision comes down to which feature set and tier structure works better for your expected usage.
TheirStack offers 4 pricing tiers compared to Seamless.AI's 3, giving you more granularity as you scale.
Both platforms offer free tiers, so you can test each one before spending anything.
Features Breakdown
- Real-time B2B contact search engine
- Email and cell phone lookups
- Pitch intelligence
- Data enrichment
- Buyer intent data (add-on)
- Job changes tracking (add-on)
- and 4 more listed below
- Job search
- Company search
- Company lookup
- Enrichment
- Exports
- Email alerts
- and 2 more listed below
Seamless.AI Key Features
- Real-time B2B contact search engine
- Email and cell phone lookups
- Pitch intelligence
- Data enrichment
- Buyer intent data (add-on)
- Job changes tracking (add-on)
- Autopilot list building (add-on)
- AI writing assistant
- Chrome extension
- Enterprise security and compliance
TheirStack Key Features
- Job search
- Company search
- Company lookup
- Enrichment
- Exports
- Email alerts
- Webhooks
- MCP server
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 Seamless.AI
- Real-time B2B contact search engine
- Email and cell phone lookups
- Pitch intelligence
- Data enrichment
- Buyer intent data (add-on)
- Job changes tracking (add-on)
- Autopilot list building (add-on)
- AI writing assistant
- Chrome extension
- Enterprise security and compliance
Listed only by TheirStack
- Job search
- Company search
- Company lookup
- Enrichment
- Exports
- Email alerts
- Webhooks
- MCP server
Integration Ecosystem
Seamless.AI Integrations
Seamless.AI connects with: Salesforce, HubSpot, Outreach, SalesLoft, Pipedrive, Microsoft Dynamics 365, Zapier.
TheirStack Integrations
TheirStack connects with: Clay, LinkedIn Audiences, Make, N8N, Zapier.
Shared Integrations
Both tools integrate with: Zapier.
Integrations listed only by Seamless.AI: Salesforce, HubSpot, Outreach, SalesLoft, Pipedrive, Microsoft Dynamics 365.
Integrations listed only by TheirStack: Clay, LinkedIn Audiences, Make, N8N.
Use Case Recommendations
Best Fit for Seamless.AI
- 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 (7 integrations)
- Teams that want to start free and scale up as needs grow
- 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 | Seamless.AI | TheirStack |
|---|---|---|
| Starting Price | Free | Free |
| Top Tier Price | Contact Sales | Contact Sales |
| Total Features Listed | 10 | 8 |
| Integrations | 7 | 5 |
| Founded | 2015 | 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
Seamless.AI and TheirStack both serve the B2B lead data and contact enrichment market. Seamless.AI offers a more accessible entry point, while TheirStack starts at $0/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 Seamless.AI and TheirStack for current information.
Frequently asked questions.
Frequently asked questions- What is the main difference between Seamless.AI and TheirStack?
- Seamless.AI is an AI-powered sales lead platform focused on real-time B2B contact search, pitch intelligence, and data enrichment. TheirStack is a job posting and technographics database that finds companies by the technologies they use and the roles they are hiring for, then enriches company lists with technographics and buying intent data.
- How much do Seamless.AI and TheirStack cost?
- Both platforms offer a free tier starting at $0 per month. Seamless.AI's paid Pro and Enterprise plans require contacting sales for pricing, while TheirStack has a usage-based App plan, an API, Webhooks and MCP plan at $49 per month for 1,500 API credits, and a Datasets plan available by contacting sales.
- Which integrations do Seamless.AI and TheirStack support?
- Seamless.AI connects with Salesforce, HubSpot, Outreach, SalesLoft, Pipedrive, Microsoft Dynamics 365, and Zapier, totaling 7 integrations. TheirStack connects with Clay, LinkedIn Audiences, Make, N8N, and Zapier, totaling 5 integrations. Zapier is the only integration both tools share.
- Which tool is better for budget-conscious teams?
- Both Seamless.AI and TheirStack are recommended for budget-conscious teams looking for an affordable data enrichment tool, since both let teams start free and scale up as needs grow. The article notes both are also suitable for enterprise buyers who prefer custom pricing and dedicated support.
- When were Seamless.AI and TheirStack founded?
- Seamless.AI was founded in 2015, while TheirStack was founded in 2021. This age difference is reflected in Seamless.AI's broader feature set of 10 listed capabilities and 7 integrations, compared to TheirStack's 8 listed features and 5 integrations.
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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