---
title: "BuiltWith alternatives in 2026: tech stack lookup APIs compared"
category: "comparisons"
url: https://keirolabs.cloud/blog/builtwith-alternative
---

## The 60-second version

**BuiltWith starts at $295 a month and Wappalyzer's API at about $250 a month, both built for sales teams buying lead lists. If you want to look up the tech stack of specific companies from code, a pay-per-lookup API costs a fraction of that.**

- **BuiltWith:** Basic $295, Pro $495, Team $995 a month ([plans](https://builtwith.com/plans)). Domain API pricing is not published; the free API returns only category counts.
- **Wappalyzer:** Pro about $250 a month with 5,000 credits, Business about $450 with 20,000; credits expire after 60 days ([pricing](https://www.wappalyzer.com/pricing/)). API access needs a paid plan.
- **[browserfoundry by Keirolabs](https://www.browserfoundry.cloud/?utm_source=keirolabs&utm_medium=blog&utm_campaign=builtwith-alternative) company API:** the `tech` field costs 2 credits per company, about $0.005 on Essential ($29.99 covers 5,625 lookups) and $0.002 on Startup. Every technology comes with the evidence it was found in.
- **Free and self-hosted:** community forks of Wappalyzer's fingerprints, if you run the scanning yourself.

Prices checked October 27, 2026.

## BuiltWith alternatives compared

| Tool | Entry price | Lookups | API | Best for |
|---|---|---|---|---|
| **BuiltWith** | $295/month | Reports on 2 technologies (Basic) | Domain API, price on request | Lead lists of every site using a technology |
| **Wappalyzer** | about $250/month | 5,000 credits, expire in 60 days | Included on paid plans | Lookups plus lead lists, browser extension |
| **browserfoundry** | $29.99/month (or 750 free credits) | 5,625 tech lookups on Essential | Yes, the product is the API | Looking up specific companies from code or an agent |
| **Self-hosted fingerprints** | free | unlimited | your own | High volume, if you maintain it |

**The real split is direction.** BuiltWith and Wappalyzer are strongest at "give me every site that uses Shopify," which needs a crawl of the whole web. If your question is "what does this company use," for a CRM record, a sales brief or an agent, you need a lookup API, and paying $295 a month for list-building you don't use is the expensive way to get it.

## What a tech stack lookup returns

**One POST with a domain returns the stack, grouped by category, with the evidence for each item.** Here is a real response for `linear.app` (trimmed):

```bash
curl -X POST https://api.keirolabs.cloud/api/v2/company \
  -H "Authorization: Bearer $KEIRO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"company": "linear.app", "fields": ["tech"]}'
```

```json
{
  "domain": "linear.app",
  "name": "Linear",
  "tech": {
    "stack": [
      { "name": "TypeScript",       "category": "Languages",         "evidence": "named in 1 of 4 engineering job posts" },
      { "name": "React",            "category": "Frameworks",        "evidence": "named in 1 of 4 engineering job posts" },
      { "name": "Next.js",          "category": "Frontend",          "evidence": "homepage code" },
      { "name": "Cloudflare",       "category": "Hosting & CDN",     "evidence": "homepage code" },
      { "name": "Google Cloud",     "category": "Hosting & CDN",     "evidence": "homepage response headers" },
      { "name": "Google Workspace", "category": "Email",             "evidence": "MX record" },
      { "name": "Postmark",         "category": "Email sending",     "evidence": "SPF record" },
      { "name": "Slack",            "category": "Business software", "evidence": "DNS verification record" },
      { "name": "LaunchDarkly",     "category": "Business software", "evidence": "DNS verification record" }
    ]
  }
}
```

**Four sources, one call:**

| Source | What it reveals |
|---|---|
| Homepage HTML and scripts | Frontend framework, analytics, chat widgets, CDN |
| Response headers | Hosting, servers, security layers |
| DNS: MX, SPF and verification records | Email provider, email-sending tools, SaaS the company has verified its domain with |
| Engineering job posts | Languages, frameworks and infrastructure the team works in, which a homepage scan can't see |

**The `evidence` field is the difference.** A row that says "SPF record" or "named in 3 of 9 job posts" can be checked and trusted in a sales email; a bare technology name can't.

## Tech stack lookup in Python

```python
import os, requests

def tech_stack(domain: str) -> dict[str, list[str]]:
    r = requests.post(
        "https://api.keirolabs.cloud/api/v2/company",
        headers={"Authorization": f"Bearer {os.environ['KEIRO_API_KEY']}"},
        json={"company": domain, "fields": ["tech"]},
        timeout=120,
    )
    r.raise_for_status()
    by_cat: dict[str, list[str]] = {}
    for t in r.json()["tech"]["stack"]:
        by_cat.setdefault(t["category"], []).append(t["name"])
    return by_cat

print(tech_stack("linear.app"))
```

**Enrich a CSV of domains:** loop over the rows, call `tech_stack`, and write a column per category. At 2 credits a lookup, 5,000 domains cost 10,000 credits, inside one Essential month.

## Ask your own question about a company's stack

**Fixed categories don't answer questions like "do they use Salesforce or HubSpot?" or "are they on AWS?".** Add `custom_fields` with your own questions, and each answer comes back with the source URL and the exact quote that supports it, or `null` when no evidence says so:

```json
{
  "company": "linear.app",
  "fields": ["tech"],
  "custom_fields": [
    { "name": "crm", "description": "Which CRM does the company use?" },
    { "name": "data_warehouse", "description": "Which data warehouse does the engineering team use?" }
  ]
}
```

Each custom field costs 2 credits.

## How accurate are tech stack detectors?

**Every detector misses what leaves no public trace.** Backend databases, internal tools and anything behind a login rarely show up in HTML or DNS. Detectors also lag when a site migrates, and old scans can report technology a company removed months ago. Three ways to judge a tool:

1. **Does it show evidence?** You can verify a claim with a source; you can only trust one without.
2. **How fresh is it?** browserfoundry scans live on each request (cached briefly); index-based tools report their last crawl.
3. **Does it read job posts?** Hiring pages are the best public signal for backend and data tooling.

## Which BuiltWith alternative should you pick?

- **You build lead lists by technology** ("every Shopify store in Germany"): BuiltWith or Wappalyzer. That needs a web-wide index.
- **You enrich known companies in a CRM, a sales tool or an agent:** a lookup API. browserfoundry charges per company and returns evidence for every result.
- **You need millions of lookups and have engineers:** run open-source fingerprints yourself.

The same endpoint also returns funding, hiring, news, pain points and people for a company in one call, which we cover in [company enrichment API alternatives](/blog/clearbit-alternatives). New accounts get 750 free credits, enough for 375 tech lookups, with no card.