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Promo Seeker: Auto-find Promo Codes with SerpAPI, Gemini & Telegram

by Khairul MuhtadinUpdated: Last update 4 days agoSource: n8n.io
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Getting Started

Promo Seeker automatically finds, verifies, and delivers active promo codes to users via Telegram or email using SerpAPI + Gemini (OpenRouter). Saves hours of manual searching and deduplicates results into an n8n Data Table for fast reuse.

Why Use This Workflow?

Time Savings: Reduces manual promo hunting from ~2 hours to ~5 minutes per query.

Cost Reduction: Cuts reliance on paid scraping tools or manual services — potential savings of $50–$200/month.

Error Prevention: Cross-references sources and enforces a 30‑day recency filter to reduce expired-code hits by ~60% vs single-source checks.

Scalability: Handles hundreds of queries per day with Data Table upserts and optional scheduling for continuous discovery.

Ideal For

  • Marketing / Growth Managers: Quickly discover competitor or partner discounts to promote in campaigns.
  • Customer Support / Operations: Respond to user requests with verified promo codes via Telegram or email.
  • Affiliate / Content Teams: Aggregate and maintain a clean promo feed for newsletters or site widgets.

How It Works

  1. Trigger: Incoming request via Webhook, Telegram message, Google Form submission, or scheduled run.
  2. Data Collection: The LangChain agent uses SerpAPI search results and Gemini (OpenRouter) to locate recent promo codes.
  3. Processing: Filter for recency (last 30 days), extract code, value, terms, and expiry.
  4. Intelligence Layer: Gemini 2.5 Pro (OpenRouter) + LangChain agent structure and verify results, outputting a standardized JSON.
  5. Output & Delivery: If a code exists in the Data Table, notify the requester via Telegram and Gmail; otherwise, return results and upsert them into the Data Table.
  6. Storage & Logging: Results stored/upserted in an n8n Data Table to prevent duplicates and enable fast lookups.

Setup Guide

Prerequisites

RequirementTypePurpose
n8n instanceEssentialExecute the workflow — import JSON to your n8n instance
SerpAPI accountEssentialWeb search results for promo code discovery
OpenRouter (Gemini) accountEssentialLanguage model (Gemini 2.5 Pro) for extraction and verification
Telegram Bot (BotFather)EssentialReceive queries and send promo notifications
Gmail OAuth2EssentialSend rich email notifications
n8n Data TablesEssentialStore and deduplicate promo code records

Get your n8n instance here: n8n instance — import the JSON and begin configuration. (Repeat link for convenience) n8n instance

Installation Steps

  1. Import the JSON workflow into your n8n instance.
  2. Configure credentials (use n8n's Credentials UI — do NOT paste keys into nodes):
    • SerpAPI: paste your SerpAPI API Key from your SerpAPI dashboard.
    • OpenRouter API: paste your OpenRouter API Key (for Gemini 2.5 Pro).
    • Telegram API: create bot via @BotFather, then add Bot Token to Telegram credentials.
    • Gmail OAuth2: use n8n's Gmail OAuth2 credential flow and authorize the account.
  3. Update environment-specific values:
    • Webhook path: /v1/promo-seeker (configured in the Webhook node) or replace with your preferred path.
    • Data Table ID: point to your own Data Table
    • Form/webhook recipient fields (email/chatId mappings).
  4. Customize settings:
    • Adjust the LangChain agent prompt (Promo Seeker Agent) for different recency windows or regional focus.
    • Change max results/limit on the Data Table node (default limit = 3).
  5. Test execution:
    • Trigger via Telegram or a POST to the webhook with sample payload:

           { "platform":"example.com", "email":"[[email protected]](/cdn-cgi/l/email-protection)" }
      
    • Confirm notifications arrive and Data Table rows are upserted.

Technical Details

Core Nodes

NodePurposeKey Configuration
SerpAPIFetch web search resultsProvide credential; adjust search params in agent prompt
Gemini 2.5Pro (OpenRouter)Extract & verify promo detailsUse OpenRouter credential; model google/gemini-2.5-pro
Promo Seeker Agent (LangChain)Orchestrates search + parsingSystem prompt enforces 30‑day recency & result format
Structured Output ParserValidates agent outputJSON schema example for platform/code/value/terms/validUntil
Data Table (Get row(s))Lookup existing promosFilters by platform; limit = 3
If (Code Exist?)Branching logicChecks existence of platform field
Data Table (Upsert row(s))Insert or update promoMapping from agent output to Data Table columns
Telegram Trigger / TelegramReceive queries & notify usersWebhook-based trigger; parse_mode = HTML for messages
GmailSend rich HTML emailsUses Gmail OAuth2 credential
Webhook / Form TriggerAlternate inputsWebhook path /v1/promo-seeker and Form trigger for manual submissions

Workflow Logic

  • On trigger, the Platform Set node normalizes the incoming query and receiver.
  • Get row(s) checks Data Table for existing promos.
    • If found: notify via Telegram and send Gmail (email template included).
    • If not found: the Promo Seeker Agent runs SerpAPI searches, parses structured output, then Upsert row(s) saves results and notifications are sent.
  • Structured Output Parser enforces correct JSON to avoid bad upserts.

Customization Options

Basic Adjustments

  • Recency window: change the agent prompt to 7/14/30 days.
  • Result limit: increase Data Table Get limit or change Upsert batch size.

Advanced Enhancements

  • Add Slack or Microsoft Teams notifications (moderate complexity).
  • Add caching layer (Redis) to reduce repeated SerpAPI calls (advanced).
  • Parallelize searches across multiple search engines (higher API usage & complexity).

Performance & Optimization

MetricExpected PerformanceOptimization Tips
Execution time8–30s per new search (depends on SerpAPI + LM response)Reduce SerpAPI page depth; cache recent results
API calls3–10 SerpAPI calls per complex queryBatch queries; use higher-quality search params
Error handlingAgent retries on malformed outputUse retry nodes and set onError strategy for downstream nodes

Troubleshooting

ProblemCauseSolution
No results returnedQuery too vague or rate-limited APIImprove query specificity; check SerpAPI quota
Gmail send failsOAuth scope not granted or token expiredReconnect Gmail OAuth2 credential in n8n
Telegram webhook not firingIncorrect bot token or webhook setupRecreate Telegram credential and check bot permissions
Duplicate rowsUpsert mapping mismatchEnsure promoCode mapping in Upsert matches structured output
Agent returns malformed JSONLM prompt too permissiveTighten the agent system prompt and validate with Structured Output Parser

Created by: khaisa Studio
Category: Marketing Automation

Tags: promo-codes, coupons, serpapi, telegram, gmail, openrouter, data-tables

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