Castle vs Sift
Castle vs Sift, compared side by side on 16 data points: what each one does, how big it is, what it has raised, the tech running each site, and what users report. We score both out of 100 on traction, team and visibility: Castle is on 60/100 and Sift on 41/100.
Where each one leads
Castle
- our overall score: 60/100 against 41/100
- agent readiness: 49/100 against 21/100
- headcount: 52 against 2
- funding raised: $9.2M against $4.3M
- LinkedIn following: 18,824 against 17
Sift
Leads on none of the measures we hold for both companies.
At a glance
| Measure | Castle | Sift |
|---|---|---|
| What it is | Developer-grade infrastructure to stop bots, abuse, and fraud by transforming user behavior into real-time signals. | Reduced Real-Time Bidding (RTB) infrastructure costs by filtering low-value impressions using machine learning. |
| Category | Cybersecurity, Threat Detection, Authentication, API Platform | Marketing, Programmatic Media, Real-Time Bidding, MFG + SUPPLY CHAIN |
| Sells toBusiness model | B2B | B2B |
| Offering | Software | Software |
| Founded | 2015 | 2017 |
| Headquarters | San Francisco, United States | Not published |
| Status | Active | Active |
Size, funding and growth
| Measure | Castle | Sift |
|---|---|---|
| Employees | 52 | 2 |
| Headcount growthLast 12 months | +24.2% | Not published |
| Total funding | $9.2M | $4.3M |
| Latest round | Series A | Seed |
| LinkedIn followers | 18,824 | 17 |
StartupHub scores
Our own 0-100 ratings. They measure company strength and site quality, not which product suits you.
| Measure | Castle | Sift |
|---|---|---|
| StartupHub scoreOur 0-100 rating | 60/100 | 41/100 |
| Traction | 52/100 | 38/100 |
| Team | 60/100 | 20/100 |
| Community | 15/100 | Not published |
| Search visibility | 36/100 | 24/100 |
| Quality | 68/100 | 48/100 |
| Agent readinessHow well an AI agent can read and act on the site | D (49/100) | F (21/100) |
| Domain ratingLink authority, 0-100 | 66/100 | Not published |
Technology
Detected on each public site, so it reflects the marketing stack as well as the product.
| Measure | Castle | Sift |
|---|---|---|
| Hosting | Netlify | Not detected |
| CDN | Netlify | Not detected |
| CMS | Lovable | Not detected |
| Frameworks | Astro, Tailwind CSS | Not detected |
| Analytics | Google Analytics 4, Google Tag Manager, PostHog | Not detected |
Castle vs Sift: common questions
Which is better, Castle or Sift?
On our 0-100 score Castle rates higher (60/100 against 41/100). The score weights traction, team, visibility and profile completeness, so it reflects company strength rather than which product suits you. We compare the two on 16 data points above: read the rows that match what you are buying for.
How do Castle and Sift compare on the numbers?
Castle leads on our overall score (60/100 against 41/100), agent readiness (49/100 against 21/100), headcount (52 against 2), funding raised ($9.2M against $4.3M), LinkedIn following (18,824 against 17).
Read the full Castle review and pricing or the Sift review and pricing. You can also browse other Castle alternatives we track.