The Stack Index / What operators run / The outbound tools operators run, by operator count
GTM Vault · The Stack Index · operator evidence only
The outbound tools operators run, by operator count
On the GTM Vault record, 16 operators described running 23 tools across the source layer, the enrichment and resolution layer and the action surface layer. Ordered by how many operators run each: Clay (7), Apollo (6), Slack (5), Instantly (4), Apify (2). The number in brackets is operators on the record, not reviews, traffic or revenue.
Updated 1 Oct 2026, the date of the latest episode or confirmation citing any tool on these layers. Cite as: GTM Vault, The Stack Index, “The outbound tools operators run, by operator count”, https://pro.gtmvault.co/stack/most-run/outbound, updated 1 Oct 2026.
How to read this page. The order is a count, not a score. Each number is how many operators described running the tool on a GTM Vault episode or in a confirmed stack, one citation per episode, in their own words. A tool named only as displaced by something else is not counted as run. Nothing is inferred from reviews, traffic or pricing, nothing here is a recommendation, and placement in the index is not for sale.
At a glance
Every tool run by more than one operator, by count. Each row jumps to who runs it and what they built.
What these layers do
Outbound is three layers working in sequence: sources that supply records, a resolution layer that decides which answer wins, and an action surface that carries the message to a person. A tool that only stores the result afterwards sits on a different layer and is not on this list.
Run by more than one operator
- 1
Clay7
Enrichment and Resolution layer. Mid-market tier. 7 operators on the record.
- Vinayak Mishra, Slang AI
Master data layer, three tables
- Garrett Wolfe, 1GTM
Account scoring and enrichment waterfall
- Umar Farooq Adam, Hitachi Vantara
Account research and enrichment
- Tim Scheuer, Oxygen
Campaign build layer, later replaced by CLI orchestration
- Elliot O'Connor, Frontier
Data and workflows behind the extension's one-click actions
- Charles Cormier, TopLeads
Enrichment and list automation
- Michael Saruggia, Clay Operator
Core of the GTM engineer stack
- 2
Apollo6
Source layer. Self-serve tier. 6 operators on the record.
- Alexander Shartsis, Skyp
Contact data and email enrichment via API
- Garrett Wolfe, 1GTM
Contact database
- Angelo Quiambao, Intellistack
Previous role at Qualified: prospecting data wrapped as an agent via its API
- Confirmed Sep 2026Mark van Oppen, SecureAuth
Contact data at SecureAuth, in heavy use
- Tim Scheuer, Oxygen
Named as a likely vendor in the email waterfall
- Charles Cormier, TopLeads
Contact data for podcast-led outbound
- 3
Slack5
Action Surface layer. Mid-market tier. 5 operators on the record.
- Alexander Shartsis, Skyp
Notification and alerting layer over MCP
- Amos Bar-Joseph, Swan AI
Interface the agent runs through
- Umar Farooq Adam, Hitachi Vantara
Rep notification fired by Outreach activity webhooks
- Angelo Quiambao, Intellistack
Previous role at Qualified: natural-language trigger for the query agent where reps work in Slack
- Michael Bartimer, Clarify
Website Visitors channel, visibility as step one of the play
- 4
Instantly4
Action Surface layer. Mid-market tier. 4 operators on the record.
- Tim Scheuer, Oxygen
Email sending and sequencing
- Michael Bartimer, Clarify
Marketing-led outbound by persona, outcomes written back to the CRM
- Charles Cormier, TopLeads
Cold email sending at $80/month, in a stack he puts at about $200/month
- Nick Velkovski, HeyReach
Email outreach, bought instead of built in-house
- 5
Apify2
Source layer. Self-serve tier. 2 operators on the record.
- Vinayak Mishra, Slang AI
Pre-built actor aggregating review sites
- Charles Cormier, TopLeads
Scraping to build prospect lists
- 6
Lead Magic2
Source layer. Self-serve tier. 2 operators on the record.
- Garrett Wolfe, 1GTM
First call in the enrichment waterfall
- Tim Scheuer, Oxygen
Named as a likely vendor in the email waterfall
- 7
Lemlist2
Action Surface layer. Mid-market tier. 2 operators on the record.
- Jai Toor, DeepLine
Verified leads exported into campaigns
- Sriharsha Guduguntla, Hyperbound
Sequencing for outbound email
- 8
Outreach2
Action Surface layer. Enterprise tier. 2 operators on the record.
- Umar Farooq Adam, Hitachi Vantara
Outbound sequencing
- Michele Shepard, Emburse
Captures SDR and BDR activity alongside Gong
- 9
ZoomInfo2
Source layer. Enterprise tier. 2 operators on the record.
- Confirmed Sep 2026Mark van Oppen, SecureAuth
Account and contact data at SecureAuth, in heavy use
- Umar Farooq Adam, Hitachi Vantara
First source in the firmographic waterfall
Run by one operator
One operator on the record each. Named here because the record holds them, not because the index ranks them lower.
These counts move with every episode
Every Show Me Your Stack episode adds operators and tools to this index. Subscribe to GTM Vault and get each one as it lands.
Common questions
- What tools do outbound teams use?
- On the GTM Vault record, 16 operators described running 23 tools across the source layer, the enrichment and resolution layer and the action surface layer. Ordered by how many operators run each: Clay (7), Apollo (6), Slack (5), Instantly (4), Apify (2). The number in brackets is operators on the record, not reviews, traffic or revenue. Every count is one citation per episode, in the operator's own words, from Show Me Your Stack, the GTM Vault Podcast or a confirmed stack.
- Which tool is run by the most operators?
- Clay, with 7 operators on the record: Vinayak Mishra (Slang AI), Garrett Wolfe (1GTM), Umar Farooq Adam (Hitachi Vantara), Tim Scheuer (Oxygen), Elliot O'Connor (Frontier), Charles Cormier (TopLeads) and Michael Saruggia (Clay Operator). It sits on the enrichment and resolution layer.
- What do these layers do?
- Outbound is three layers working in sequence: sources that supply records, a resolution layer that decides which answer wins, and an action surface that carries the message to a person. A tool that only stores the result afterwards sits on a different layer and is not on this list. Source: Where raw records enter: companies, people, firmographics, scraped listings. Enrichment and Resolution: Waterfall enrichment, dedupe, entity matching across sources. Action Surface: Where the rep or agent works, and where sends actually go out.
- Is this a ranking of the best tools?
- No. The order is the number of operators who described running the tool on a GTM Vault episode, nothing else. The index carries no score, no sponsored placement and no editorial preference. Placement is not for sale and no count is edited. Updated 1 Oct 2026.
- How many operators are behind these numbers?
- 16 distinct operators across these layers. A tool appears only once an operator described running it in a working system; tools named only as displaced by something else are not counted as run.
Also: The tools GTM engineers run, by operator count · The enrichment and data tools operators run, by operator count · The AI tools operators run in their GTM stack, by operator count · Compare two tools: Clay vs ZoomInfo · Apollo vs ZoomInfo · Clay vs Apollo · All layers