Custom AI models connect to Smartling at two primary integration points: the Translation API for batch job processing and the Real-Time Translation (RTT) API for dynamic content. For batch workflows, your model is deployed as a custom machine translation provider, invoked via Smartling's submit translation job or async translation endpoints. This allows project managers to route specific content—like technical documentation, legal clauses, or marketing copy with a unique brand voice—to your domain-optimized engine instead of a generic MT service. The integration handles cost tracking, post-editing (PEP) analysis, and quality estimation scores just like a first-party connector.
Integration
AI Integration for Smartling Custom AI Development

Where Custom AI Models Fit in the Smartling Stack
A technical blueprint for integrating custom-trained AI translation models into Smartling's sandbox and production workflows.
For real-time or interactive use cases, such as translating user-generated content in a help desk or dynamic e-commerce attributes, the RTT API provides a low-latency path. Here, your custom model acts as a stateless service, receiving translation requests via webhook or direct API call from Smartling's connector framework. Implementation requires careful management of context windows, since Smartling sends strings individually or in small batches; you must design your model's inference pipeline to receive and honor any contextual metadata (like keyId, fileUri, or custom context fields) passed from the TMS to maintain consistency.
Rollout follows a sandbox-first governance model. Develop and test your integration using Smartling's Sandbox API and dedicated test projects, where you can validate output quality, latency, and cost against a subset of real translation memory. Before promotion to production, establish a human-in-the-loop review workflow, using Smartling's Workflow API to automatically route all AI-translated content to a specific "Custom AI Review" stage staffed by senior linguists. This creates an audit trail and a feedback loop for model retraining. For ongoing operations, implement logging to capture model inputs, outputs, and reviewer acceptance rates, enabling continuous evaluation and drift detection against your quality benchmarks.
Smartling APIs and Webhooks for Custom AI Integration
Smartling's API Architecture for AI
Smartling's REST API provides granular control over translation assets and workflows, making it ideal for custom AI integration. Key surfaces for AI development include:
- Translation Jobs API: Programmatically create jobs, assign content, and route strings. Use this to inject AI-powered pre-translation or to create separate jobs for AI-vs-human review based on content risk scores.
- Strings & Files API: Directly push and pull source content and translations. This is the primary surface for feeding content to custom AI models and retrieving AI-generated suggestions for human post-editing.
- Translation Memory (TM) API: Retrieve and update TM entries. Integrate custom AI to semantically search the TM (beyond exact matches) using a vector database, or to auto-clean and deduplicate TM entries.
- Glossary API: Manage approved terminology. Connect AI models for automated term extraction from source documents and to enforce terminology compliance on AI-generated translation outputs.
These APIs allow you to treat Smartling as the system of record while running custom AI logic in parallel, syncing results bidirectionally.
High-Value Use Cases for Custom AI in Smartling
For development teams building domain-specific translation models, integrating them securely with Smartling's APIs unlocks new levels of quality and efficiency. These use cases detail where custom AI can connect to the platform's data model and workflow automation layer.
Domain-Specific Translation Engine Integration
Deploy a custom fine-tuned LLM (e.g., for legal, medical, or technical jargon) as a new MT provider in Smartling's workflow. Use the Connectors API to route high-complexity strings to your model based on file tags or project metadata, while standard content uses generic MT. This reduces post-editing effort for specialized content by 40-60%.
Automated Brand & Compliance QA Agent
Build an AI agent that acts as a custom QA step via webhook. After translation, the agent analyzes segments against a vector database of brand guidelines, glossaries, and regulatory clauses (e.g., GDPR, HIPAA). It flags violations directly in Smartling's job list with suggested fixes, turning a manual review sprint into a continuous automated check.
Intelligent Translation Memory Enrichment
Augment Smartling's TM with semantic search via a integrated vector database. When translators query the TM, your custom model retrieves conceptually similar past translations—not just 100% matches—providing context for ambiguous terms. This integration uses the Translation Memory API to read/write enriched entries, boosting translator confidence and consistency.
Predictive Job Scoping & Routing
Integrate a predictive model with the Projects API to analyze incoming source files. The model estimates post-editing effort, optimal vendor selection, and risk score based on content type, historical data, and glossary coverage. Automatically tag jobs, set priorities, and assign them to appropriate linguist pools, reducing project setup from a manual process to an automated, data-driven workflow.
Dynamic Glossary Management & Suggestion
Create an AI service that monitors source commits and Smartling projects via webhook to auto-suggest new terminology. It analyzes source strings against existing glossaries and product documentation, proposing new terms with definitions and context. Project managers review and approve suggestions via a custom dashboard, which then pushes approved terms to Smartling's Glossary API, keeping terminology current.
Real-Time Translator Copilot Interface
Build a secure, context-aware copilot that integrates into the translator's workflow via a custom plugin or sidebar. It uses RAG against your internal knowledge base (product docs, past decisions) and the Smartling Editor API to provide in-line suggestions, answer questions about ambiguous source strings, and explain glossary term usage—all without leaving the translation interface.
Example AI-Augmented Workflows in Smartling
For teams building custom AI models for domain-specific translation, these workflows illustrate how to securely integrate them with Smartling's sandbox and production APIs to augment the core localization pipeline.
Trigger: A new source file (e.g., API documentation, engineering spec) is uploaded to a designated Smartling project.
Context Pulled: The integration uses the Smartling Files API to download the source content. Metadata (project ID, file URI, customModel: technical_v1 flag) is passed to the custom AI service.
AI Action: The custom fine-tuned model (e.g., trained on proprietary technical jargon and past approved translations) processes the source segments, generating initial translation suggestions. The model's confidence score and a diff against the generic MT suggestion are logged.
System Update: The custom AI service posts the suggestions back to Smartling via the Translation Job API, creating a new job or adding the suggestions as a preferred translation memory candidate for linguists.
Human Review Point: All suggestions are flagged as machine_suggested with a provider: custom_tech_model tag. Smartling's workflow is configured to require linguist review for all segments, but the custom suggestions are presented as the primary option, significantly reducing post-editing effort.
Implementation Architecture: Connecting Custom Models to Smartling
A technical blueprint for integrating bespoke AI translation models with Smartling's sandbox and production APIs.
Integrating a custom AI model—such as a domain-specific translation engine or a fine-tuned LLM—requires a secure, event-driven architecture that plugs into Smartling's job lifecycle. The core integration points are the Translation Job API for creating and managing work, and the String API for pushing source content and pulling translated segments. A production implementation typically uses a middleware service that listens for webhooks from your source systems (e.g., a CMS push, a code commit), prepares the payload, and calls Smartling's API to create a job. This service then orchestrates the custom model, routing specific content strings based on complexity, domain, or cost rules defined in your configuration.
For the AI model itself, hosting is critical. Options include a containerized model behind a secure REST endpoint in your VPC or a managed service like Azure AI or Google Vertex AI. The integration service passes source strings and relevant context (from a connected vector database of past translations or brand guidelines) to the model endpoint. The returned AI translation is then posted back to the specific Smartling string via the API, often flagged with a custom vendor tag like custom_ai_v1 for tracking. This flow should include a quality estimation step and the ability to route low-confidence outputs to a human-in-the-loop review queue within Smartling's workflow before final approval.
Governance and rollout require careful planning. Start in Smartling's sandbox environment to validate API interactions and cost routing logic without affecting live projects. Implement robust logging, tracing (using tools like LangSmith or Weights & Biases), and audit trails for every AI-suggested translation to monitor model drift and business impact. Key technical considerations include managing API rate limits, handling batch failures, and setting up automated rollback procedures if the custom model's output quality degrades. A phased rollout—perhaps beginning with low-risk, high-volume content like internal knowledge base articles—allows you to measure acceptance rates and time savings before scaling to customer-facing materials.
Code and Payload Examples
Connecting Custom Models to Smartling's Sandbox
For secure testing, connect your custom AI model to Smartling's sandbox environment. This pattern uses a proxy service to handle authentication, request formatting, and cost logging before calling your model endpoint. The key is to maintain Smartling's job and string identifiers throughout the process for traceability.
pythonimport requests from smartling import SmartlingClient # Hypothetical SDK # Proxy endpoint that receives Smartling webhook def handle_smartling_translation_request(request_payload): """Process a batch of strings from Smartling sandbox.""" job_id = request_payload['job']['jobId'] strings = request_payload['strings'] # Enrich context from Smartling's Translation Memory (TM) enriched_strings = [] for s in strings: tm_matches = fetch_tm_matches(s['sourceString'], s['localeId']) enriched_strings.append({ 'smartling_hash': s['hashcode'], 'source': s['sourceString'], 'locale': s['localeId'], 'tm_context': tm_matches, 'custom_metadata': s.get('customMetadata', {}) }) # Call your custom model endpoint model_response = call_custom_model(enriched_strings) # Format response back to Smartling API spec return { 'jobId': job_id, 'translations': [ { 'hashcode': item['smartling_hash'], 'translatedString': item['translation'], 'translationQuality': 'CUSTOM_AI' } for item in model_response ] }
Realistic Operational Impact of Custom AI Integration
This table illustrates the tangible workflow and efficiency changes when a custom AI model (e.g., for domain-specific translation) is integrated into Smartling's sandbox and production APIs, moving beyond generic machine translation.
| Development & Integration Phase | Before Custom AI | After Custom AI | Implementation Notes |
|---|---|---|---|
Model Training & Fine-tuning | Weeks of manual data collection and labeling | Days of automated data pipeline execution | Leverage Smartling TM/Glossary APIs for training data; automate with vector stores |
Sandbox Testing & Validation | Manual, sample-based testing in isolation | Automated regression and quality scoring via API | Integrate evaluation suite with Smartling sandbox webhooks for continuous validation |
Production API Integration | Complex, one-off connector development | Standardized MCP-like agent orchestration | Use Smartling's webhook and job API for event-driven model invocation |
Translation Suggestion Latency | Seconds to minutes for external MT calls | Sub-second for hosted, domain-tuned models | Requires co-located inference endpoint; cost vs. speed trade-off for high-volume projects |
Terminology & Style Adherence | Post-hoc QA checks flag inconsistencies | Pre-emptive style scoring and term validation | Custom model embeds brand glossary; outputs include confidence scores for risky segments |
Model Update & Retraining Cycle | Quarterly or manual trigger | Continuous, triggered by TM/glossary updates | Automate retraining pipelines triggered by Smartling webhooks on approved translations |
Operational Cost Profile | High, variable per-word MT costs | Predictable, compute-based with lower marginal cost | Shift from per-word fees to infrastructure spend; optimal for high-volume, niche domains |
Governance, Security, and Phased Rollout
A structured approach to deploying custom AI translation models into Smartling's production environment, balancing innovation with enterprise-grade control.
Deploying a custom AI model into Smartling's workflow requires a clear governance framework. This starts with defining a sandbox-to-production promotion path using Smartling's API environments. Your custom model should be containerized and deployed to a secure inference endpoint (e.g., AWS SageMaker, Azure ML). Access is then controlled via API keys scoped to specific Smartling projects or accounts, ensuring the model only processes authorized translation jobs. All model inputs (source strings) and outputs (translation suggestions) should be logged to a secure audit trail, linked to the Smartling job ID, translator ID, and a model version tag for full traceability.
A phased rollout is critical for managing risk and measuring impact. Start with a closed pilot, routing only low-risk, high-volume content types (e.g., internal knowledge base articles, UI button labels) through the custom model within a single Smartling project. Use Smartling's workflow stages and translator groups to enforce a human-in-the-loop review for all AI-suggested translations. Key metrics to track include translator post-edit distance (how much they change the AI output), throughput gain, and quality scores from Smartling's built-in QA checks. This data validates the model's ROI before expanding its scope.
For broader rollout, implement content routing logic using Smartling's job creation API and custom fields. Based on metadata like content_domain, target_market, and risk_tier, your orchestration layer can decide whether to send a string to your custom model, a third-party MT provider, or directly to human translation. Establish a model monitoring and rollback protocol to detect performance drift—such as a drop in translator acceptance rate or a spike in QA violations—and automatically revert to a previous model version or a fallback provider. This operationalizes AI as a reliable, governed component of your localization pipeline, not a black-box experiment.
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Intelligent Analysis, Decision & Execution
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Give teams answers from docs, tickets, runbooks, and product data with sources and permissions.
Useful when people spend too long searching or get different answers from different systems.

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Use AI to route work, draft outputs, trigger actions, and keep approvals and logs in place.
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Useful when AI needs to be part of the product, not a separate tool.
Frequently Asked Questions for Custom AI Development with Smartling
Common technical and strategic questions for teams building and deploying custom AI models (e.g., domain-specific translation engines) into Smartling's sandbox and production environments.
A secure integration typically follows this pattern:
- Authentication & Environment: Use Smartling's API v2 with dedicated service accounts. Begin development in the Sandbox API environment using test projects and non-sensitive content.
- Secure Model Hosting: Host your custom model on a secure, scalable cloud service (AWS SageMaker, Azure ML, GCP Vertex AI) with a private API endpoint. Never embed API keys or model weights in client-side code.
- Orchestration Layer: Build a lightweight middleware service (e.g., in Python/Node.js) that:
- Receives translation job payloads from Smartling via webhook or polled API calls.
- Calls your custom model's endpoint with the source strings and any contextual metadata (e.g.,
project_id,file_uri,custom_fields). - Applies post-processing (length checks, placeholder validation).
- Posts the AI-generated translations back to Smartling's Job Batches API (
/jobs-api/v3/projects/{projectId}/jobs/{jobId}/batches).
- Security Posture: Implement mutual TLS (mTLS) for service-to-service communication, store all secrets in a vault, and ensure all data in transit and at rest is encrypted. Your middleware should enforce strict input/output validation to prevent injection attacks.

About the author
Prasad Kumkar
CEO & MD, Inference Systems
Prasad Kumkar is the CEO & MD of Inference Systems and writes about AI systems architecture, LLM infrastructure, model serving, evaluation, and production deployment. Over 5+ years, he has worked across computer vision models, L5 autonomous vehicle systems, and LLM research, with a focus on taking complex AI ideas into real-world engineering systems.
His work and writing cover AI systems, large language models, AI agents, multimodal systems, autonomous systems, inference optimization, RAG, evaluation, and production AI engineering.
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