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Translation API for Python

This guide shows you how to use the Langbly translation API in Python. Langbly is Google Translate v2 compatible and charges $5 per 1M additional input characters—a 75% lower usage rate than Google Cloud Translation Basic's published $20 rate.

Installation​

pip install langbly

Quick Start​

from langbly import Langbly

client = Langbly(api_key="your-api-key-here")

result = client.translate(
    q="Hello, how are you?",
    target="nl"
)

print(result.translated_text)
# Output: "Hallo, hoe gaat het met je?"

Get Your API Key​

  1. Sign up at langbly.com/signup and add payment details to activate API access
  2. Create an API key in your dashboard
  3. The first 500K input characters each month are included after activation

Translate Text​

Basic Translation​

from langbly import Langbly

client = Langbly(api_key="your-api-key-here")

# English to Dutch
result = client.translate(q="Good morning!", target="nl")
print(result.translated_text)  # "Goedemorgen!"

# English to German
result = client.translate(q="Good morning!", target="de")
print(result.translated_text)  # "Guten Morgen!"

With Source Language​

By default, Langbly auto-detects the source language. You can specify it explicitly:

result = client.translate(
    q="Bonjour le monde",
    target="en",
    source="fr"
)
print(result.translated_text)  # "Hello world"

HTML Translation​

Translate HTML content while preserving tags:

result = client.translate(
    q="<p>Welcome to our <strong>website</strong></p>",
    target="nl",
    format="html"
)
print(result.translated_text)
# "<p>Welkom op onze <strong>website</strong></p>"

Batch Translation​

Translate multiple strings in a single API call:

results = client.translate(
    q=["Hello", "Goodbye", "Thank you"],
    target="nl"
)

for r in results:
    print(r.translated_text)
# "Hallo"
# "Tot ziens"
# "Dank je"

Error Handling​

The SDK provides typed exceptions:

from langbly import Langbly, AuthenticationError, RateLimitError

client = Langbly(api_key="your-api-key-here")

try:
    result = client.translate(q="Hello", target="nl")
except AuthenticationError:
    print("Invalid API key")
except RateLimitError as e:
    print(f"Rate limited. Retry after {e.retry_after} seconds")
except Exception as e:
    print(f"Error: {e}")

Auto-Retry​

The SDK automatically retries on 429 (rate limit) and 5xx (server error) responses with exponential backoff:

# Retries are enabled by default
client = Langbly(
    api_key="your-api-key-here",
    max_retries=3,  # default
)

Translate Files​

Translate a JSON i18n File​

import json
from langbly import Langbly

client = Langbly(api_key="your-api-key-here")

# Load source file
with open("en.json") as f:
    source = json.load(f)

# Translate all values
translated = {}
keys = list(source.keys())
values = list(source.values())

results = client.translate(q=values, target="nl")
for key, result in zip(keys, results):
    translated[key] = result.translated_text

# Save translated file
with open("nl.json", "w") as f:
    json.dump(translated, f, ensure_ascii=False, indent=2)

Translate a CSV File​

import csv
from langbly import Langbly

client = Langbly(api_key="your-api-key-here")

with open("products.csv") as f:
    reader = csv.DictReader(f)
    rows = list(reader)

# Translate product names
names = [row["name"] for row in rows]
results = client.translate(q=names, target="nl")

for row, result in zip(rows, results):
    row["name_nl"] = result.translated_text

# Write output
with open("products_nl.csv", "w", newline="") as f:
    writer = csv.DictWriter(f, fieldnames=rows[0].keys())
    writer.writeheader()
    writer.writerows(rows)

Environment Variables​

Instead of passing the API key directly, use an environment variable:

export LANGBLY_API_KEY=your-api-key-here
from langbly import Langbly

# Automatically reads LANGBLY_API_KEY from environment
client = Langbly()

Google Translate Migration​

If you're migrating from Google Translate, the Langbly API is compatible:

# Before (Google Translate)
# from google.cloud import translate_v2 as translate
# client = translate.Client()
# result = client.translate("Hello", target_language="nl")

# After (Langbly)
from langbly import Langbly
client = Langbly(api_key="your-key")
result = client.translate(q="Hello", target="nl")
print(result.translated_text)

Next Steps​