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Quickstart Guide

Get up and running with the Blockline API in three simple steps. You’ll learn how to authenticate, make your first request, and analyze transaction context.

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Prerequisites

  • A Blockline account (sign up here)
  • A Solana transaction signature to analyze
  • Basic knowledge of HTTP APIs and curl/your programming language of choice

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Step 1: Get Your API Key

1

Sign up for Blockline

Visit blockline.soltop.sh and create an account. New users get a free trial to explore the API.
2

Navigate to API Keys

Once logged in, go to Dashboard → API Keys
3

Generate a new key

Click “Create New API Key”, give it a name (e.g., “Production”), and save the key securely.
Your API key is shown only once! Copy it immediately and store it securely. It looks like: sk_live_xxxxxxxxxx...

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Step 2: Make Your First Request

Let’s analyze a Solana transaction to see who traded before and after it. 
curl -X POST https://api.soltop.sh/analyze-trade \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer sk_live_YOUR_API_KEY" \
  -d '{
    "signature": "pHXgUjY4cVvi5orXuK3b66MBhF2W3MpXruRGKodqTWze7354iVQ66k1rWCzyWTU7UDeebojPTpW9ZmVv9Dn12cg",
    "account_id": "FnmStvzQ27Pm4U8r3M6gPD7mnk6ST6HwraPsoNmYpump",
    "slot_range": 4
  }'

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Understanding the Request

  • signature: Your transaction signature (base58-encoded, 87-88 characters)
  • account_id: The market/pool address your transaction touched (base58-encoded, 32-44 characters)
  • slot_range: Number of slots before/after to search (default: 4, max: 100)
Don’t have a transaction to test with? Use the example signature above to see how it works!

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Step 3: Understand the Response

The API returns all transactions that touched the same market within ±4 slots of your transaction: 
{
  "success": true,
  "data": {
    "original_transaction": {
      "signature": "pHXgUjY4cVvi...",
      "slot": 370537741,
      "poh_tick": 23714415424,
      "signer": "FnmStvzQ27Pm..."
    },
    "results_by_slot": [
      {
        "slot": 370537741,
        "slot_offset": 0,
        "transactions": [
          {
            "signature": "abc123...",
            "poh_tick_offset": -150000,
            "signer": "7xKXtg2CW...",
            "is_original": false
          }
        ]
      }
    ],
    "summary": {
      "total_matching_transactions": 15,
      "slots_with_activity": 3
    }
  }
}

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Key Fields Explained

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poh_tick_offset
integer
Negative = transaction happened before yours (potential front-runner) Zero = your transaction Positive = transaction happened after yours (potential back-runner)
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slot_offset
integer
Negative = earlier slot/block Zero = same slot as your transaction Positive = later slot/block

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Common Errors

Cause: Invalid or missing API key Solution: Check that you’re including the Authorization: Bearer sk_live_... header with a valid API key
Cause: Subscription required or expired Solution: Ensure your subscription is active (trial, active, or grace period) at your dashboard
Cause: Invalid signature format or parameters Solution: Verify your signature is base58-encoded and 87-88 characters long
Cause: Rate limit exceeded (6 requests/minute) Solution: Wait for the retry_after_seconds time before retrying

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Next Steps

Now that you’ve made your first request, explore more capabilities:

Detect Front-Running

Learn how to identify transactions that front-ran yours

Find Sandwich Attacks

Detect if you were sandwiched by MEV bots

Get Transaction Details

Fetch detailed transaction metadata including fees and tokens

Code Examples

See complete integration examples in JavaScript and Python
You’re all set! You now know how to authenticate and make requests to the Blockline API.

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Need Help?