How to Build a CS2 Skin Price Alert Bot

Alert types that work

Type	Rule	Example
Absolute price	`price <= X` on market M	YouPin Redline FT under ¥140
Cross-market spread	`price_A / fx(A) - price_B / fx(B) > Y%`	Skinport 8% above YouPin after fees
Percent move	`change_24h <= -Z%`	Dump alert on CSFloat
Phase-specific	Same as above + `phase` filter	Ruby Karambit only

Architecture

┌─────────────┐     every N min      ┌──────────────────┐
│  Scheduler  │ ──────────────────► │ POST /v1/prices/  │
│  (cron)     │                     │ latest (≤100)     │
└─────────────┘                     └────────┬─────────┘
                                           │
                                           ▼
                                  ┌──────────────────┐
                                  │ State store      │
                                  │ prev price, phase│
                                  └────────┬─────────┘
                                           │
              crossing detected            ▼
                                  ┌──────────────────┐
                                  │ Discord / TG /   │
                                  │ webhook          │
                                  └──────────────────┘

Respect plan rate limits. Batch up to 100 items per POST.

Poll example

curl -s -X POST "https://api.cspriceapi.com/v1/prices/latest" \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "items": [
      "AK-47 | Redline (Field-Tested)",
      "M4A1-S | Printstream (Field-Tested)"
    ],
    "markets": ["youpin", "skinport", "csfloat"]
  }'

Crossing logic (with hysteresis)

Avoid alert spam when price oscillates ±0.5%:

def crossed_below(prev: float | None, curr: float, threshold: float, hysteresis: float = 0.005) -> bool:
    if prev is None:
        return curr <= threshold
    # Fire when crossing down through threshold; reset when clearly above
    if prev > threshold >= curr:
        return True
    if curr > threshold * (1 + hysteresis):
        return "reset"  # allow re-arm
    return False

Store armed per (name, phase, market, rule_id).

Discord webhook (minimal)

import requests

def notify_discord(webhook_url: str, content: str) -> None:
    requests.post(webhook_url, json={"content": content}, timeout=10)

# Example message
msg = (
    "🔔 **AK-47 | Redline (FT)** YouPin ¥138.50 "
    "(crossed below ¥140)\n"
    "Skinport: €17.90 | CSFloat: $124\n"
    "<https://cspriceapi.com/market-hub/comparison>"
)
notify_discord("https://discord.com/api/webhooks/...", msg)

Rules that prevent false alerts

Rule	Why
Match `phase`	Phase 4 dip ≠ Ruby dip
`count >= 5`	Ignore single-listing noise
Stale check	Skip if `updated_at` older than 15 min on fast markets
Fee-adjusted spread	Raw price gap ≠ profit
One alert per crossing	Hysteresis re-arm

Buy-order alerts (exit price)

Monitor YouPin bids for "someone wants to buy above X":

curl -s "https://api.cspriceapi.com/v1/prices/youpin/buyorder" \
  -H "x-api-key: YOUR_API_KEY"

Compare top bid movement vs your inventory fair value.

No-code alternatives

Tool	Best for
Price Comparison	Cross-market gaps ranked by ROI, no cron
Price Comparison	Saved market pairs + ROI filters
Chrome extension Pro	Price alerts while browsing listings
Trending	24h movers without custom rules

Production checklist

Discord testkey or dashboard API key
Quickstart — verify auth
Log updated_at per row — freshness matters
Handle partial POST failures (per-item errors if returned)
Backtest thresholds on history before live alerts