How to Validate a Startup Idea With APIs: Reddit, Product Hunt, TikTok & Trends

Search "how to validate a startup idea" and you'll find dozens of guides — IdeaDose, Unbuilt Lab, Reddinbox — all describing roughly the same workflow: search Reddit for your problem, sort by top, count the posts by hand; check Product Hunt for existing competitors; eyeball a Google Trends chart. It's good advice. It's also entirely manual, which means you can't re-run it next week, can't compare five ideas side by side, and can't turn it into anything repeatable.

The signals are the same either way. The only thing that changes is whether a human clicks through five tabs, or a script — or an AI agent — calls five documented endpoints and hands back structured JSON.

The five signals, and what each one actually proves

• Reddit — pain-point evidence in the audience's own words, and roughly how often the problem comes up.
• Product Hunt — whether someone is already building this, and how their launch was received.
• Google Trends — whether search interest for the category is rising, flat, or cooling.
• Google Autocomplete — the exact phrasing real people search, not the phrasing you assumed.
• SimilarWeb — how large the existing players already are, so 'no competition' claims get checked against real traffic.

No single signal is decisive. Reddit tells you the pain is real but says nothing about market size. Product Hunt tells you who else is building it but says nothing about whether their launch actually worked. Trends and Autocomplete describe search behavior, not buying intent. SimilarWeb sizes the incumbents but can't tell you if there's still room. Read together, they triangulate — which is the same reason the manual-workflow guides above tell you to check more than one source; this just automates the checking.

A real worked example: "an app that cancels unused subscriptions"

This is a real run against a real idea, not a mocked example — every number below came back from a live API call.

Reddit. A broad sitewide search for "cancel unused subscriptions app" returned mostly noise — unrelated posts that happened to share keywords. That's a real, useful lesson on its own: Reddit's search ranks on loose keyword matching, not relevance, so a bare query wastes the signal. Scoping the same search to r/personalfinance and sorting by top surfaced a genuinely on-topic pain point — a 60+-comment thread about a gym that made it deliberately impossible to cancel a membership, forcing the poster to go through their bank. Lesson for anyone running this themselves: always scope to a specific relevant subreddit, never search sitewide.

Product Hunt. Two real, current, small competitors turned up: Subwatch ("Track subscriptions, cancel unused ones, save money weekly") and SubRemindr ("Track subscriptions & bills with just your email") — both recent, both with zero reviews yet. The category is active but not yet won by a small player.

Google Trends. Interest in "subscription tracker app" (US, trailing 12 months) climbed from a baseline of ~17 in August 2025 to a peak of 100 in the week of June 14–20, 2026 — then cooled back down to 14 by late August 2026. Real interest, but not a steady climb — more of a spike than a trend.

Google Autocomplete. Real, distinct queries: cancel unused subscriptions, app to cancel unused subscriptions, spot and cancel unused subscriptions, how to cancel unused subscriptions on iphone. Confirms the demand is real and gives the actual phrasing to target in copy, not a guess.

TikTok. This is where the honest picture sharpened. A keyword search didn't surface a gap — it surfaced the incumbents: Rocket Money, Hiatus, Trim, and Monarch Money all showed up in existing creator content, one post racking up 56,600 plays. This category already has name recognition among the exact audience a new entrant would target.

SimilarWeb. Checking the biggest name found above, rocketmoney.com: ~3.68M monthly visits, global rank 11,611, category rank 63 in Finance/Banking. Its own brand keyword ("rocket money") is worth an estimated $324K/month in equivalent ad spend.

Two ways to run this yourself

Script it

Each signal is one documented endpoint. A minimal validation script calls all five and prints a scorecard:

GET /reddit/search?q=<problem-phrasing>&subreddit=<relevant-sub>&sort=top&time=year
GET /producthunt/search?query=<category>
GET /google-trends/explore/interest-over-time?keywords=<category>&geo=US
GET /google/suggest?q=<seed-phrase>
GET /similarweb/web?domain=<top-competitor-domain>
x-api-key: YOUR_API_KEY

See Market Research API, Reddit Social Listening, and Product Hunt Research for the full field reference on each.

Or just ask your agent

Crawlora ships a hosted MCP server (mcp.crawlora.net/mcp), so instead of writing a script, connect it to an agent and describe the idea in plain language — the agent calls the tools itself. This post's own worked example above was produced exactly this way. Verified connection commands, checked live for this post:

Then a single prompt does the work:

"Validate this startup idea: [idea]. Check Reddit (scoped to the most relevant subreddit) for pain-point volume, Product Hunt for existing competitors, Google Trends for the interest trend, Google Autocomplete for real search phrasing, and SimilarWeb for the size of the biggest existing player. Give me a scorecard and an honest verdict."

No API docs to read, no script to maintain — the agent reads the tool descriptions and calls them itself.

Run this against your own idea

2,000 free credits/month, no card required. Try the Reddit, Product Hunt, and Trends endpoints in the Playground first.

Open the PlaygroundSee the MCP server