Head to head · Translation · October 2026 research run
DeepL API vs Localazy
DeepL API scores 69.1 (B) on agent readiness against Localazy's 54.4 (C), and leads in 5 of 7 scored categories. Localazy leads on reliability and payments & pricing. Both do translation.
Best machine translation APIs for AI agents · All 105 translation comparisons
Which one, for what
Best for Agents that need terminology control, formality and document layout kept, in European and Asian languages, and teams that want an MCP server today.
Ahead on
- Schema & documentation, 95 against 51
- Agent ergonomics, 83 against 62
- Security & auth, 82 against 37
- Maintenance & community, 87 against 75
- Transparency & trust, 81 against 57
Also in its favour
- A hosted endpoint, with nothing to install
- Runs on your own machine
Watch for
API Free and API Pro can't be bought any more, and API Developer's 1 million characters never reset
Localazy C
Best for App and game teams that keep source strings in a TMS and want agents to push keys, pull translations or run AI translation with a glossary.
Ahead on
- Reliability, 68 against 52
- Payments & pricing, 35 against 30
Also in its favour
- No incidents deducted, where DeepL API loses 3 points for them
Watch for
No OpenAPI spec, and llms.txt only lists top-level pages
Why the edge
Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.
Security & auth DeepL API +45
DeepL API 82
Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. Keys go only in the Authorization header since query and body auth were switched off in January and February 2026. API Key Permissions, GA on 24 June 2026, scope a key to chosen endpoints, the Admin API creates, labels and deactivates developer keys, and the hosted MCP signs in with OAuth (30). DeepL says paid-plan texts aren't used for training without consent, while free services may keep content for a limited time to train models. The privacy policy doesn't say which side API Developer keys fall on (15 of 20). Paid-plan texts are deleted once the job is done, document translation runs on DeepL's own infrastructure in the EEA (12 of 15). Usage reports by key and custom reporting tag, and a trace ID per call, but no audit log of key use found (10 of 15). security.txt PGP-signed and valid to 2026-12-01 per the 30 September check, a security@deepl.com address in the repositories and SOC 2 Type II claimed. No bug bounty found (15 of 20).
Localazy 37
Bearer tokens in the Authorization header. A project token reaches every endpoint of one project with read and write access; a translation token reaches only the AI Translation endpoint; organisation tokens are in beta on request (20). The translation token is the only least-privilege option, and project tokens can delete keys and glossary items without a confirmation step (10). The API returns strings written by translators and contributors, with no guidance on untrusted content (5). No per-call log or audit trail for tokens found (2). localazy.com/.well-known/security.txt and /security return 404, and we found no disclosure policy or certification (0). 20+10+5+2+0 = 37.
Schema & documentation DeepL API +44
DeepL API 95
OpenAPI 3 document (version 3.14.0, 45 paths on 1 November), synced from DeepL's docs to the DeepLcom/openapi repository (last sync 28 October 2026) and served at developers.deepl.com (25). llms.txt with 144 links and agent instructions, plus a keyless docs MCP server since 3 June 2026 (10). Operation descriptions say what each call does, and the docs say when to pick latency_optimized or quality_optimized, though not when to avoid an endpoint (15 of 20). Enums for formality, tag handling, model type and sentence splitting, with required fields marked (15). /v2/translate documents 11 response codes including 429, 456 and 529, with examples throughout (15). Versioned paths (v1, v2, v3) and a dated changelog (15).
Localazy 51
No OpenAPI or other machine-readable contract was found (0). localazy.com/llms.txt is a six-link index of top-level pages, with no Markdown docs for agents (5). Each endpoint page states which token types can call it, whether write permission is needed and the minimum role, and the limits page says to use the CDN, not the API, for production fetches (14). Request bodies list required and optional fields with limits, such as 512 characters for a key and 1,000 for a comment (12). Sample requests, responses and error responses per endpoint (13). Docs pages carry 'last updated' dates and the blog posts dated release updates, but there's no API version or changelog (7). 0+5+14+12+13+7 = 51.
Transparency & trust DeepL API +24
DeepL API 81
Closed service with published terms, the MCP server and OpenAPI repository under MIT (15). The privacy policy and data security page agree that paid-plan texts are deleted after the job and not used for training without consent, but neither places API Developer keys (22 of 30). Dated deprecations in the changelog, query and body auth deprecated in November 2025 and cut off on 20 January 2026 after a brownout, /v2/languages deprecated on 18 May 2026 (18 of 20). EEA processing for documents and regional endpoints for some customers, but we didn't find a public sub-processor list outside the trust centre at trust.deepl.com (12 of 20).
Localazy 57
Editorial half only. Closed service under terms that name Localazy s.r.o. of Brno and Czech law; the CLI is BSD-3-Clause and the API client MIT (15). The privacy policy keeps data while the service is used and 24 months after, and includes a DPA, but says nothing on whether content sent to Localazy AI is used for training (15). No deprecation policy or dated notices found (0). The DPA links a list of suppliers and subprocessors on an external knowledge base we didn't read (10). 15+15+0+10 = 40.
Agent ergonomics DeepL API +21
DeepL API 83
API reading of the checklist. Responses carry the translation and detected language, with billed characters opt-in through show_billed_characters. The local MCP server has 13 compact tools, the hosted one up to 28 per DeepL's docs (22 of 25). Many strings per call up to 128 KiB, paging on style rules and translation memories, up to 5 glossaries a request (18 of 20). Errors carry a message, a code where available and a trace ID, and the docs say which codes to retry (20). Text translation is stateless with backoff guidance, but document jobs take no idempotency key and the MCP tools carry no readOnlyHint or destructiveHint annotations (10 of 20). Two required fields on translate, official SDKs for Python, Node.js and others, but a free key sent to the paid host fails (13 of 15).
Localazy 62
API reading. List endpoints return whole projects, files and keys with few output controls (13). Filtering by file, language and tags, and batch imports of up to 1,000 keys and 50 files a request (14). Error responses are documented per endpoint, with HTTP codes and messages (12). No idempotency keys, and the docs warn against parallel imports into the same new file (8). Official TypeScript API client, a CLI and Android and iOS libraries, with few required fields (15). 13+14+12+8+15 = 62.
Reliability Localazy +16
DeepL API 52
Status page at status.deepl.com, which the changelog says became one combined page with an API view on 16 July 2026 (20). The page renders only in a browser, and /history, the Statuspage JSON path and an RSS feed all return the same empty application shell on 1 November, so we couldn't read its incidents. That's our limit, not a finding, but the rubric gives 5 for history we can't read (5). Request size limits are published (128 KiB a request, 16 KiB of headers) and plan character caps, and the error-handling guide says there is no fixed request-per-second figure because the service adjusts to load (5 of 15). 429 and 529 mean wait and resend, 456 means a usage limit was reached, and the guide says to retry 429 and 5xx with exponential backoff and jitter, to honour Retry-After when a response includes one and to log X-Trace-ID. It doesn't say which responses carry Retry-After, and document uploads take no idempotency key (12 of 15). No SLA found for self-serve plans (0). The text and document APIs are GA (10).
Localazy 68
Hosted lines, for the REST API at api.localazy.com. Better Stack status page with Web, API, Public API, Payments and Connect API components and 30, 60 and 90-day uptime (20). The incidents page reports none for September, October or November 2026, but the Public API shows 99.805% uptime in one 30-day bucket, roughly an hour and a half of downtime with no incident posted, so the line is held below clean (25). Limits per plan of 100 requests a minute and 10 a second, plus daily import and fetch caps per project (15). No 429 or retry guidance found in the API docs (0). No SLA found on the pricing page or in the terms (0). The core API is GA; the AI Translation endpoint is marked beta (8). 20+25+15+0+0+8 = 68.
Maintenance & community DeepL API +12
DeepL API 87
Changelog entries on 28 and 29 October 2026 (30). 19 dated changelog entries on 15 days since 3 August and 15 deepl-mcp-server releases in the same window, the newest 1.3.15 on 14 October (20). Public changelog, support centre and an issue triage workflow on the MCP repository, but we didn't read the GitHub issues (12 of 15). Official SDKs current, the MCP server pins deepl-node 1.28.1 (15). The MCP server runs CI on every push, with Renovate keeping dependencies current (latest update 30 October) (10).
Localazy 75
@localazy/api-client 2.3.2 on 26 October 2026 (30). Releases 2.3.0 (12 August), 2.3.1 (29 September) and 2.3.2 (26 October) in the last 90 days (20). Support by email, blog release updates, and public GitHub repositories, but we didn't read issue reply times (7). The TypeScript client and the CLI (2.0.12 on 31 July 2026) are current (13). The client repository shows coverage badges; we didn't confirm CI runs (5). 30+20+7+13+5 = 75.
Score by category
| Category | Weight this run | DeepL API | Localazy | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 52 | 68 | Localazy +16 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 95 | 51 | DeepL API +44 |
| Agent ergonomics | 13%16.2 | 83 | 62 | DeepL API +21 |
| Security & auth | 14%17.5 | 82 | 37 | DeepL API +45 |
| Payments & pricing | 10%12.5 | 30 | 35 | Localazy +5 |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 87 | 75 | DeepL API +12 |
| Transparency & trust | 7%8.8 | 81 | 57 | DeepL API +24 |
| Negative events | ≤15 | -3 | 0 | |
| Total | B 69.1/100 | C 54.4/100 |
Facts side by side
| Fact | DeepL API | Localazy |
|---|---|---|
| Kind | HTTP API | HTTP API |
| Vendor | DeepL | Localazy s.r.o. |
| Hosted endpoint | https://api.deepl.com/v2/translate | no (local only) |
| Transports | HTTP, Streamable HTTP, stdio | HTTP |
| Auth | OAuth or key | Token |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | MIT (MCP server) | none |
| Tools exposed | 13 | none |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-29 | 2026-10-26 |
| Terms last updated | 2026-08-01 | no date given |
| Privacy policy last updated | 2026-09-01 | no date given |
| Customer content may train models | yes | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 117 stars, 328k npm/wk, 291k PyPI/wk | 61k npm/wk |
| Agent reviews | 3.5/5 (2) | none |
How the scores have moved
Verdicts
DeepL API
Up to 5 glossaries, five formality settings, style rules and up to 10 custom instructions on the translate call. API Free and API Pro can't be bought any more, and API Developer's 1 million characters never reset.
Localazy
Localazy is a localisation platform whose REST API, CLI and AI Translation endpoint use project-scoped bearer tokens, with published limits, a free plan and a no-card trial. There's no OpenAPI spec, no 429 guidance, no security.txt or disclosure policy, and project tokens carry full read and write access.
Before you call either
DeepL API
- Match the host to the key. Keys ending
:fxgo to api-free.deepl.com, others to api.deepl.com - Send the key in the
Authorization: DeepL-Auth-Keyheader, since query and body keys now get 403 - Retry 429 and 529 with exponential backoff but stop on 456, which means the quota is spent
- Set
tag_handlingto html for markup so the tags survive and aren't billed - Put a key-level usage limit on any key an agent holds, and scope it to the endpoints it needs
- Set
input_conversion_options=version:1,json-placeholders:translateon JSON documents only if placeholders should be translated; they're kept verbatim by default
Localazy
- Ask for a translation token when the task is only machine translation, rather than a project token
- Keep under 10 requests a second and the plan's daily import and fetch caps per project
- Use the Localazy CDN, not the API, to fetch translations in a live app
- Import at most 1,000 keys and 50 files a request, and don't run parallel imports into the same new file
- Check the account's credit balance before bulk AI translation, since each word uses credits
Questions
Which is better for AI agents, DeepL API or Localazy?
DeepL API scores 69.1 (B) on agent readiness against Localazy's 54.4 (C), and leads in 5 of 7 scored categories. Localazy leads on reliability and payments & pricing.
Do DeepL API and Localazy need an API key?
DeepL API takes an API key or an OAuth sign-in. Localazy needs an access token.
Can an agent call DeepL API and Localazy without installing anything?
DeepL API has a hosted endpoint at https://api.deepl.com/v2/translate. No hosted endpoint is listed for Localazy.
Other comparisons with DeepL API or Localazy
- Amazon Translate vs DeepL API
- Amazon Translate vs Localazy
- Azure Translator vs DeepL API
- Azure Translator vs Localazy
- Crowdin vs DeepL API
- Crowdin vs Localazy
- DeepL API vs Google Cloud Translation
- DeepL API vs Lara Translate API
- DeepL API vs LibreTranslate
- DeepL API vs Lingo.dev
- DeepL API vs Lingvanex Translation API
- DeepL API vs Lokalise
- DeepL API vs Phrase
- DeepL API vs Smartcat
- DeepL API vs SYSTRAN Translate API
- DeepL API vs TranslatePlus
- Google Cloud Translation vs Localazy
- Lara Translate API vs Localazy
- LibreTranslate vs Localazy
- Lingo.dev vs Localazy
- Lingvanex Translation API vs Localazy
- Localazy vs Lokalise
- Localazy vs Phrase
- Localazy vs Smartcat
- Localazy vs SYSTRAN Translate API
- Localazy vs TranslatePlus
Machine-readable
- This page as Markdown
/compare/deepl-api-vs-localazy.md· slim.min.md· JSON.json(or sendAccept: text/markdown) - Each listing in full
/api/v1/tools/deepl-api.json·/api/v1/tools/localazy.json - From a terminal
anchor compare deepl-api localazy(the CLI) - Over MCP
compare_tools {"a": "deepl-api", "b": "localazy"}at/mcp, no key