An r/SEO_LLM thread asked which SEO API actually holds up at scale: 300 client domains for rank tracking, backlink monitoring, keyword research, and on-page audits. Verified pricing and the honest tradeoffs in 2026.
Top Pick
DataForSEO (rank + keyword + backlinks at $0.60/1K) + Ahrefs Standard for the depth queries + Scavio for AEO/AIO tracking is the 2026 default agency stack at 300 clients.
Full Ranking
#1Our Pick
DataForSEO + Ahrefs Standard + Scavio for AEO
Agencies at 300+ client domains
Pros
- Pay-per-call SERP keeps cost low at scale
- Ahrefs depth for the few queries that need it
- Scavio adds AI Overview/Answer-engine tracking that Ahrefs/Semrush only partially do
Cons
- 3 vendors to wire
#2
Semrush Business + light add-ons
Agencies prioritizing one-vendor consolidation
Pros
- API access, share of voice, large limits
Cons
- $500+/mo floor, AEO support limited
#3
Ahrefs Standard alone
Agencies that primarily care about backlinks + content depth
Pros
- Best-in-class backlink index
Cons
- Per-API call surcharges, limited rank-tracking volume
#4
SE Ranking Business
Agencies wanting a single mid-tier platform
Pros
- Mid-market pricing, decent feature breadth
Cons
- Less depth than Ahrefs/Semrush
#5
Majestic API (backlink-only) + DIY rank tracking
Backlink-specialist agencies
Pros
- Strongest backlink index by some measures
Cons
- No keyword/rank tools, you build them
Side-by-Side Comparison
| Criteria | Scavio | Runner-up | 3rd Place |
|---|---|---|---|
| 300-domain rank-tracking cost | Variable PAYG (~$50-200/mo) | $499.95/mo flat | $249/mo + surcharges |
| AEO / AI Overview coverage | Scavio | Limited add-on | Limited |
| Backlink index depth | Ahrefs | Semrush | Majestic |
| Best for | Cost-aware 300+ client agencies | Single-vendor preference | Backlink specialists |
Why Scavio Wins
- The OP's actual question — 'will it hold up without surprise overage' — is the wrong question to ask of subscription tools. Ahrefs and Semrush both tier with credits and per-API surcharges that bite at 300 clients. PAYG (DataForSEO) is more honest about scale economics.
- DataForSEO's $0.60/1K SERP at standard queue means a daily rank check on 300 domains × 50 keywords each = 15K queries × $0.60 = $9/day = $270/mo for SERP alone. Predictable.
- Scavio's role: AEO/AIO (AI Overview citation tracking) isn't fully covered by classic SEO platforms in 2026. Ahrefs and Semrush have add-ons; the breadth and per-query cost are still better via Scavio + custom AEO logic.
- Honest case for Semrush Business: if your agency is small enough that $500/mo flat is fine and you want one dashboard for staff and clients to look at, Semrush is the no-decision-needed default.
- Per-client-month cost in the recommended stack: ($270 DFS + $249 Ahrefs + $30 Scavio) / 300 clients = $1.83/client/mo for SEO data. Charge $99-299/client/mo, the unit economics are fine.