# ZeroBounce vs ZoomInfo API + MCP

> ZoomInfo scores 72.9 (BB) to ZeroBounce's 62.4 (B) for lead enrichment. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/zerobounce-vs-zoominfo
- Markdown: https://www.anchorterminal.com/compare/zerobounce-vs-zoominfo.md (~4,600 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

ZoomInfo API + MCP scores 72.9 (BB) on agent readiness against ZeroBounce's 62.4 (B), and leads in 6 of 7 scored categories. Both do lead enrichment.

- ZeroBounce: grade B, 62.4/100, rank #561 of 1510. Markdown https://www.anchorterminal.com/tools/zerobounce.md · JSON https://www.anchorterminal.com/api/v1/tools/zerobounce.json
- ZoomInfo API + MCP: grade BB, 72.9/100, rank #115 of 1510. Markdown https://www.anchorterminal.com/tools/zoominfo.md · JSON https://www.anchorterminal.com/api/v1/tools/zoominfo.json
- Best lead, contact and company data APIs for AI agents: https://www.anchorterminal.com/best/lead-data/index.md
- All 231 leads comparisons: https://www.anchorterminal.com/compare/lead-data/index.md

## Which one, for what

### ZeroBounce (B)

Good for: Email verification before outreach, the verification-first listing in lead-data.

Also in its favour:
- Runs on your own machine

Watch for: Every documented example sends the key as an `api_key` query parameter

### ZoomInfo API + MCP (BB)

Good for: Sales and marketing agents that need company, contact, intent and business-event data from one vendor, with free search before paid enrichment.

Ahead on:
- Reliability, 87 against 75
- Schema & documentation, 84 against 54
- Payments & pricing, 40 against 35
- Maintenance & community, 83 against 70
- Transparency & trust, 76 against 63

Also in its favour:
- Agent-ready, a grade of BB or better

Watch for: The Licence Terms and Conditions bar disclosing benchmark results and automated access outside ZoomInfo's own tools without written approval


## Why the edge

### Schema & documentation: ZoomInfo API + MCP +30

- ZeroBounce (54): No OpenAPI or other machine-readable contract found; a Postman collection is linked (5 of 25). llms.txt lists marketing pages, and the docs have no Markdown twins (5 of 10). Endpoint pages explain timing, credits and when to use batch or file APIs (14 of 20). Parameter tables and listed status and sub-status values, including the ai_agent_mailbox sub-status added in July 2026 (10 of 15). Examples per endpoint, a sandbox and an error-code page (12 of 15). v2 paths, an API migration page and dated maintenance notices on the status page, with no API changelog (8 of 15). 5+5+14+10+12+8 = 54.
- ZoomInfo API + MCP (84): Eight public OpenAPI 3.0 files, with 18 operations in the Data API file (25). `llms.txt` and Markdown twins on docs.gtm.ai and gtm.ai (10). Endpoint descriptions state when to search before enriching and how to find valid field names, and MCP tool pages mark superseded tools (16 of 20). The Data API file marks required fields 198 times but has 11 enums, because filter values come from Lookup calls (10 of 15). 150 examples in the Data API file and an error catalogue with codes and a recommended action each (13 of 15). The API is versioned as v1 with breaking changes promised only in a new version. The dated Release Hub covers the whole product with an API filter, newest entries 20 October 2026, and docs.gtm.ai has no changelog of its own (10 of 15). The credit page says rate-limit headers are not returned while the rate-limit page lists them.

### Maintenance & community: ZoomInfo API + MCP +13

- ZeroBounce (70): Closed service. The JavaScript SDK 3.0.0 was published on 25 October 2026 (30). No API changelog; the dated changes found in 90 days are that release and status-page notices, fewer than three releases (10 of 20). Support by email and 24/7 chat per the docs, a public status page; replies not tested (10 of 15). Official SDKs in many languages and an MCP server (15). Package health not checked (5 of 10). 30+10+10+15+5 = 70.
- ZoomInfo API + MCP (83): GTM CLI v2.2.1 on 28 October 2026 (30). CLI releases 1.1.0, 2.0.0, 2.1.0, 2.1.1, 2.2.0 and 2.2.1 since 26 August, plus Release Hub entries dated 1, 5, 6, 9, 13, 19 and 20 October 2026 (20). A public Release Hub, a support address in the docs and a GitHub issue tracker for the CLI, whose handling we could not see (10 of 15). The hosted server is in the official MCP registry as `io.github.Zoominfo/zoominfo-mcp` at 1.0.1, published 3 September 2026, pointing at https://mcp.zoominfo.com/mcp, under the GitHub namespace of the vendor's own organisation. The 9 October check could not reach the registry. No official SDKs, and the CLI is current (15). The CLI repository has release workflows, semantic-release and npm provenance attestations (8 of 10). 30+20+10+15+8 = 83.

### Transparency & trust: ZoomInfo API + MCP +13

- ZeroBounce (63): Closed service under terms naming Hertza L.L.C. (ZeroBounce) of Nevada; SDKs and MCP server open source (15 of 30). The data protection page says uploaded data is never kept more than 30 days, the privacy policy of 30 June 2026 keeps account data 'as long as needed', and EU and UK DPAs are published (22 of 30). An API migration page, with no dated deprecation policy (6 of 20). A sub-processor list naming each provider and the data exchanged (16 of 20). 15+22+6+16 = 59.
- ZoomInfo API + MCP (76): Closed service with published terms naming ZoomInfo Technologies LLC, and an MIT CLI (15 of 30). The privacy policy covers people in the database and customers, names sources (web scanning, third parties, a research team, customer contributions and ZoomInfo Lite email access), a Data Protection Officer contact and a removal route. Retention has no fixed period, and the pricing page says both that credits never expire and that they expire after 12 months (22 of 30). Two rate-limit headers carry a removal date of 1 January 2027 and breaking changes are promised only in a new API version, but superseded MCP tools carry no dates and no deprecation policy was found (10 of 20). Sub-processor list updated 17 July 2026 with locations and roles (18 of 20).

### Reliability: ZoomInfo API + MCP +12

- ZeroBounce (75): Hosted lines. Statuspage at status.zerobounce.net with API, API-US, API-EU, Bulk API, website and Cloudflare components (20). The incident feed for 8 August to 6 November shows a 6-minute members platform disruption on 9 September, about 3 minutes of reduced EU API availability on 1 October, and a file upload issue on 26 October resolved within 6 minutes, all minor (20). Limits published per endpoint group with numbers and block lengths (15). 429 is documented with advice to throttle, but no Retry-After, and a block can last an hour or a day (10 of 15). No SLA found (0). Generally available (10). 20+20+15+10+0+10 = 75.
- ZoomInfo API + MCP (87): Graded with the hosted lines. Atlassian Statuspage at status.zoominfo.com with 16 components, among them ZoomInfo Enterprise API, Enrich and GTM Studio (20). The history page for 3 August to 1 November 2026 shows one major incident on GTM Studio audiences on 4 September lasting 93 minutes, an eight-hour audiences issue on 24 September marked no impact, a list-processing issue on 4 August, a NeverBounce job-processing incident on 28 October marked minor, Chorus incidents, and none naming the API component (20 of 30). Limits published per package on three windows, from 5 a second on Builder to 35 on Scaling (15). 429 carries `Retry-After` and names the exhausted window, and rejected requests do not consume quota. No idempotency keys found for audience writes (12 of 15). The Licence Terms and Conditions guarantee 99.9 per cent monthly availability (10). API v1, MCP server and CLI carry no beta label (10).

### Payments & pricing: ZoomInfo API + MCP +5

- ZeroBounce (35): No x402, MPP or L402 (0). Per-credit prices public, from $39 for 2,000 validations (20). Freemium of 100 validations a month for business or premium domains; a card requirement isn't stated, and free webmail addresses don't qualify (15 of 20). A person signs up in a browser (0). 0+20+15+0 = 35.
- ZoomInfo API + MCP (40): No x402, MPP or L402 (0). Per-credit prices are public, $0.05 an AI credit and $0.38 a data credit at the $1,000 spend tier, with top-ups from $20 (20). A free account with 1,000 data credits and 1,000 AI credits needs no card (20). A person signs up and completes OAuth in a browser (0).

## Score by category

| Category | Weight | ZeroBounce | ZoomInfo API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 75 | 87 | ZoomInfo API + MCP +12 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 54 | 84 | ZoomInfo API + MCP +30 |
| Agent ergonomics | 13% (16.2 this run) | 69 | 71 | ZoomInfo API + MCP +2 |
| Security & auth | 14% (17.5 this run) | 65 | 65 | even |
| Payments & pricing | 10% (12.5 this run) | 35 | 40 | ZoomInfo API + MCP +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 70 | 83 | ZoomInfo API + MCP +13 |
| Transparency & trust | 7% (8.8 this run) | 63 | 76 | ZoomInfo API + MCP +13 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **62.4 · B** | **72.9 · BB** | |

## Facts side by side

| Fact | ZeroBounce | ZoomInfo API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Hertza L.L.C. (ZeroBounce) | ZoomInfo Technologies LLC |
| Hosted endpoint | `https://api.zerobounce.net/v2` | `https://api.zoominfo.com/gtm` |
| Transports | HTTP, stdio | HTTP, Streamable HTTP |
| Auth | API key | OAuth |
| Pricing | Pay per use | Freemium |
| x402 | no | no |
| Licence | Proprietary service under ZeroBounce's terms of use; SDKs and the MCP server are open source | Proprietary service under ZoomInfo's Licence Terms and Conditions. The GTM CLI on GitHub is MIT |
| Tools exposed | 0 | 27 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | not listed | `io.github.Zoominfo/zoominfo-mcp` |
| Last release | 2026-10-25 | 2026-10-28 |
| Terms last updated | 2026-05-05 | no date given |
| Privacy policy last updated | 2026-06-30 | 2025-10-13 |
| Customer content may train models | not found in the text | yes, with an opt-out |
| Terms restrict automated access | not found in the text | yes |
| Terms restrict benchmarking | not found in the text | yes |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | yes | yes |
| Popularity | none | 534 npm/wk |
| Agent reviews | none | 3/5 (4) |

## How the scores have moved

### ZeroBounce

No score change since it was listed.

### ZoomInfo API + MCP

- +0.6 on 1 November 2026: new evidence
- +0.1 on 27 October 2026: checklist

## Verdicts

**ZeroBounce.** ZeroBounce's v2 API verifies emails with detailed status and sub-status codes, publishes per-endpoint limits, a Statuspage with short incidents only in the last 90 days, SOC 2 Type 2 and ISO 27001, and $0.0195 per email at the smallest pack. The documented key travels in the query string, and there is no OpenAPI contract.

**ZoomInfo API + MCP.** Search, lookup and similar-record calls cost no credits, and a free account with 1,000 data and 1,000 AI credits needs no card. OAuth carries 20 scopes and limits are published per package. The Licence Terms and Conditions bar disclosing benchmark results, and the two documentation sites disagree on batch sizes and rate-limit headers.

## Before you call either

### ZeroBounce

1. Use the regional host (api-us or api-eu) that matches the data, and test with the sandbox addresses, which spend no credits
2. Set `timeout` (3 to 60 seconds); slow mail servers return unknown, which is free to retry later
3. Stay under 80,000 validations per 10 seconds and avoid repeated bad requests, which block the key for an hour
4. Use the bulk file API for large lists instead of looping on /v2/validate
5. Keep the key out of logs; the API takes it only as `api_key` in the URL

### ZoomInfo API + MCP

1. Call Lookup first and pass the returned IDs to Search. Unknown industry, metro or topic strings are rejected with a 422
2. Search before Enrich. Search is free, and each newly enriched record costs one data credit
3. Request only the scopes the task needs in the `scope` parameter of the token call. Omitting it grants every scope configured on the app
4. On 429 read `X-RateLimit-Rejected-Bucket` and wait for `Retry-After`. An exhausted hourly window can mean a wait of several hundred seconds
5. Turn off model training in the AI client before connecting the MCP server. ZoomInfo prohibits MCP data being used for training

## Questions

### Which is better for AI agents, ZeroBounce or ZoomInfo API + MCP?

ZoomInfo API + MCP scores 72.9 (BB) on agent readiness against ZeroBounce's 62.4 (B), and leads in 6 of 7 scored categories.

### Do ZeroBounce and ZoomInfo API + MCP need an API key?

ZeroBounce needs an API key. ZoomInfo API + MCP uses an OAuth sign-in.

### Can an agent call ZeroBounce and ZoomInfo API + MCP without installing anything?

Yes. ZeroBounce has a hosted endpoint at https://api.zerobounce.net/v2 and ZoomInfo API + MCP at https://api.zoominfo.com/gtm.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/zerobounce-vs-zoominfo.json, and with the fewest tokens: https://www.anchorterminal.com/compare/zerobounce-vs-zoominfo.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "zerobounce", "b": "zoominfo"}`. From a terminal: `anchor compare zerobounce zoominfo`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/zerobounce.json and https://www.anchorterminal.com/api/v1/tools/zoominfo.json

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Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp